Revert "[mono-runtimes] Try to download Mono archive before building mono (#2265)"

This reverts commit f970cd5.

Unfortunately, it [broke the build][0]:

	  libtool:   error: Could not determine the host path corresponding to
	  libtool:   error: Could not determine the host path corresponding to
	  libtool:   error:   '/Users/builder/jenkins/workspace/xamarin-android/xamarin-android/external/mono/sdks/builds/android-host-mxe-Win64-debug/mono/mini/.libs'
	  libtool:   error:   '/Users/builder/jenkins/workspace/xamarin-android/xamarin-android/external/mono/sdks/builds/android-host-mxe-Win64-debug/mono/mini/.libs'
	  libtool:   error: Continuing, but uninstalled executables may not work.

Looks like the MXE+Windows build side was broken. :-(

Revert commit f970cd5 until we figure things out.

[0]: https://jenkins.mono-project.com/view/Xamarin.Android/job/xamarin-android/1207/

Author: jonpryor

build-tools/xa-prep-tasks/Xamarin.Android.BuildTools.PrepTasks/GitCommitHash.cs

@@ -16,9 +16,6 @@ public sealed class GitCommitHash : Git
 		[Output]
 		public                  string      AbbreviatedCommitHash       { get; set; }
 
-		[Output]
-		public                  string      CommitHash       { get; set; }
-
 		protected   override    bool        LogTaskMessages             {
 			get { return false; }
 		}
@@ -41,18 +38,17 @@ public override bool Execute ()
 
 		protected override string GenerateCommandLineCommands ()
 		{
-			return "rev-parse HEAD";
+			return "log --no-color --first-parent -n1 --pretty=format:%h";
 		}
 
 		protected override void LogEventsFromTextOutput (string singleLine, MessageImportance messageImportance)
 		{
 			if (string.IsNullOrEmpty (singleLine))
 				return;
-			if (singleLine.Length < 40) {
-				Log.LogError ("Commit hash `{0}` is shorter than required length of {1} characters", singleLine, 40);
+			if (singleLine.Length < RequiredHashLength) {
+				Log.LogError ("Abbreviated commit hash `{0}` is shorter than required length of {1} characters", singleLine, RequiredHashLength);
 				return;
 			}
-			CommitHash = singleLine;
 			AbbreviatedCommitHash = singleLine.Substring (0, RequiredHashLength);
 		}
 	}

external/mono

@@ -1,9 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <ItemGroup>
-    <_MonoBcl Include="bcl" />
-  </ItemGroup>
-
   <ItemGroup>
     <_MonoRuntime Include="armeabi-v7a" Condition=" $(AndroidSupportedTargetJitAbisForConditionalChecks.Contains (':armeabi-v7a:')) ">
       <Strip>$(AndroidToolchainDirectory)\toolchains\armeabi-v7a-clang\bin\arm-linux-androideabi-strip</Strip>
@@ -64,16 +60,27 @@
       <OutputMonoBtlsFilename></OutputMonoBtlsFilename>
       <OutputMonoPosixHelperFilename>libMonoPosixHelper</OutputMonoPosixHelperFilename>
     </_MonoRuntime>
-    <_MonoRuntime Include="host-$(HostOS)" Condition="$(AndroidSupportedHostJitAbisForConditionalChecks.Contains (':$(HostOS):')) And ( '$(HostOS)' == 'Darwin' Or '$(HostOS)' == 'Linux' )">
+    <_MonoRuntime Include="host-Darwin" Condition="$(AndroidSupportedHostJitAbisForConditionalChecks.Contains (':Darwin:'))">
+      <Strip>strip</Strip>
+      <StripFlags>-S</StripFlags>
+      <OutputRuntimeFilename>libmonosgen-2.0</OutputRuntimeFilename>
+      <NativeLibraryExtension>dylib</NativeLibraryExtension>
+      <OutputProfilerFilename>libmono-profiler-log</OutputProfilerFilename>
+      <OutputAotProfilerFilename>libmono-profiler-aot</OutputAotProfilerFilename>
+      <OutputMonoBtlsFilename></OutputMonoBtlsFilename>
+      <OutputMonoPosixHelperFilename>libMonoPosixHelper</OutputMonoPosixHelperFilename>
+      <BuildTests>True</BuildTests>
+    </_MonoRuntime>
+    <_MonoRuntime Include="host-Linux" Condition="$(AndroidSupportedHostJitAbisForConditionalChecks.Contains (':Linux:'))">
       <Strip>strip</Strip>
       <StripFlags>-S</StripFlags>
       <OutputRuntimeFilename>libmonosgen-2.0</OutputRuntimeFilename>
-      <NativeLibraryExtension Condition=" '$(HostOS)' == 'Darwin' ">dylib</NativeLibraryExtension>
-      <NativeLibraryExtension Condition=" '$(HostOS)' == 'Linux' ">so</NativeLibraryExtension>
+      <NativeLibraryExtension>so</NativeLibraryExtension>
       <OutputProfilerFilename>libmono-profiler-log</OutputProfilerFilename>
       <OutputAotProfilerFilename>libmono-profiler-aot</OutputAotProfilerFilename>
       <OutputMonoBtlsFilename></OutputMonoBtlsFilename>
       <OutputMonoPosixHelperFilename>libMonoPosixHelper</OutputMonoPosixHelperFilename>
+      <BuildTests>True</BuildTests>
     </_MonoRuntime>
   </ItemGroup>
 
@@ -84,13 +91,15 @@
       <InstallBinaries>true</InstallBinaries>
       <InstallPath Condition="$(AndroidSupportedHostJitAbisForConditionalChecks.Contains (':Darwin:'))">Darwin/</InstallPath>
       <InstallPath Condition="$(AndroidSupportedHostJitAbisForConditionalChecks.Contains (':Linux:'))">Linux/</InstallPath>
+      <PackageOptions>llvm-llvm32_CC="$(HostCc32)" llvm-llvm32_CXX="$(HostCxx32)"</PackageOptions>
     </_LlvmRuntime>
 
     <_LlvmRuntime Include="llvm64" Condition=" ($(AndroidSupportedTargetAotAbisForConditionalChecks.Contains (':arm64:')) Or $(AndroidSupportedTargetAotAbisForConditionalChecks.Contains (':x86_64:'))) And '$(HostBits)' == '64' ">
       <ExeSuffix></ExeSuffix>
       <InstallBinaries>true</InstallBinaries>
       <InstallPath Condition="$(AndroidSupportedHostJitAbisForConditionalChecks.Contains (':Darwin:'))">Darwin/</InstallPath>
       <InstallPath Condition="$(AndroidSupportedHostJitAbisForConditionalChecks.Contains (':Linux:'))">Linux/</InstallPath>
+      <PackageOptions>llvm-llvm64_CC="$(HostCc64)" llvm-llvm64_CXX="$(HostCxx64)"</PackageOptions>
     </_LlvmRuntime>
 
     <_LlvmRuntime Include="llvmwin32" Condition=" ($(AndroidSupportedTargetAotAbisForConditionalChecks.Contains (':win-armeabi-v7a:')) Or $(AndroidSupportedTargetAotAbisForConditionalChecks.Contains (':win-x86:'))) ">