Fix the RV64 and LA64 builds

Author: tannergooding

src/libraries/System.Private.CoreLib/src/System/Math.cs

@@ -1198,7 +1198,7 @@ public static double MinMagnitude(double x, double y)
         [Intrinsic]
         public static double ReciprocalEstimate(double d)
         {
-#if MONO
+#if MONO || TARGET_RISCV64 || TARGET_LOONGARCH64
             return 1.0 / d;
 #else
             return ReciprocalEstimate(d);
@@ -1215,7 +1215,7 @@ public static double ReciprocalEstimate(double d)
         [Intrinsic]
         public static double ReciprocalSqrtEstimate(double d)
         {
-#if MONO
+#if MONO || TARGET_RISCV64 || TARGET_LOONGARCH64
             return 1.0 / Sqrt(d);
 #else
             return ReciprocalSqrtEstimate(d);

src/libraries/System.Private.CoreLib/src/System/MathF.cs

@@ -316,7 +316,7 @@ public static float MinMagnitude(float x, float y)
         [Intrinsic]
         public static float ReciprocalEstimate(float x)
         {
-#if MONO
+#if MONO || TARGET_RISCV64 || TARGET_LOONGARCH64
             return 1.0f / x;
 #else
             return ReciprocalEstimate(x);
@@ -334,7 +334,7 @@ public static float ReciprocalEstimate(float x)
         [Intrinsic]
         public static float ReciprocalSqrtEstimate(float x)
         {
-#if MONO
+#if MONO || TARGET_RISCV64 || TARGET_LOONGARCH64
             return 1.0f / Sqrt(x);
 #else
             return ReciprocalSqrtEstimate(x);