Revert "[compiler-rt] Disable tests for unavailable builtins (#158664)"

This reverts commit e9e166e,
and the follow-up fix 6567070.

These changes unlocked tests to run on architectures where they
didn't run before, showing up as test failures like in
https://lab.llvm.org/buildbot/#/builders/66/builds/19787.

Author: mstorsjo

compiler-rt/test/builtins/Unit/fixunstfdi_test.c

@@ -1,11 +1,12 @@
+// XFAIL: target=aarch64-{{.*}}-windows-{{.*}}
 // RUN: %clang_builtins %s %librt -o %t && %run %t
 // REQUIRES: librt_has_fixunstfdi
 
 #include <stdio.h>
 
-#include "int_lib.h"
+#if _ARCH_PPC || __aarch64__ || __arm64ec__
 
-#if defined(CRT_HAS_TF_MODE)
+#include "int_lib.h"
 
 // Returns: convert a to a unsigned long long, rounding toward zero.
 //          Negative values all become zero.
@@ -34,7 +35,7 @@ char assumption_3[sizeof(long double)*CHAR_BIT == 128] = {0};
 
 int main()
 {
-#if defined(CRT_HAS_TF_MODE)
+#if _ARCH_PPC || __aarch64__ || __arm64ec__
     if (test__fixunstfdi(0.0, 0))
         return 1;
 

compiler-rt/test/builtins/Unit/multc3_test.c

@@ -1,12 +1,12 @@
+// XFAIL: target=aarch64-{{.*}}-windows-{{.*}}
 // RUN: %clang_builtins %s %librt -o %t && %run %t
 // REQUIRES: librt_has_multc3
 
 #include <stdio.h>
 
-#include "int_lib.h"
-
-#if defined(CRT_HAS_128BIT) && defined(CRT_HAS_F128)
+#if _ARCH_PPC || __aarch64__ || __arm64ec__
 
+#include "int_lib.h"
 #include <math.h>
 #include <complex.h>
 
@@ -348,7 +348,7 @@ long double x[][2] =
 
 int main()
 {
-#if defined(CRT_HAS_128BIT) && defined(CRT_HAS_F128)
+#if _ARCH_PPC || __aarch64__ || __arm64ec__
     const unsigned N = sizeof(x) / sizeof(x[0]);
     unsigned i, j;
     for (i = 0; i < N; ++i)