cmake: add -Wno-unused-function to dns_sd_windows.c

We use an external 'mdns.h' in the Windows to do dns-sd for Windows.
We don't use all the functions on purpose, so don't warn when we use that file.

Set -Werror on Travis and AppVeyor to catch issues on mingw

Signed-off-by: Robin Getz <[email protected]>

Author: rgetz

CMakeLists.txt

@@ -163,8 +163,8 @@ if (MSVC)
 		add_compile_options(/WX)
 	endif()
 elseif (CMAKE_COMPILER_IS_GNUCC OR CMAKE_C_COMPILER_ID STREQUAL "Clang")
-	if(DEFINED ENV{TRAVIS} AND DEFINED ENV{CI})
-		message(STATUS "Running in a Travis-CI environment, setting -Werror")
+	if(DEFINED ENV{CI} AND (DEFINED ENV{TRAVIS} OR DEFINED ENV{APPVEYOR}))
+		message(STATUS "Running in CI environment (Travis or AppVeyor), setting -Werror")
 		set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
 	endif()
 endif()
@@ -307,6 +307,9 @@ if(WITH_NETWORK_BACKEND)
 	elseif(WIN32)
 		set(HAVE_DNS_SD ON)
 		list(APPEND LIBIIO_CFILES dns_sd_windows.c dns_sd.c)
+		if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_C_COMPILER_ID STREQUAL "Clang")
+			set_source_files_properties(dns_sd_windows.c PROPERTIES COMPILE_FLAGS "-Wno-unused-function")
+		endif()
 		message(STATUS "Building with mdns, A Public domain mDNS/DNS-SD library in C ")
 	else()
 		message(STATUS "Building without DNS-SD (Zeroconf) support")