Add fast math as a condition for errhandling via exceptions

Author: vhscampos

libc/include/llvm-libc-macros/math-macros.h

@@ -51,9 +51,9 @@
 #define __LIBC_SUPPORTS_MATH_ERRNO 1
 #endif
 
-#if (defined(__arm__) || defined(_M_ARM) || defined(__thumb__) ||              \
+#if defined(__FAST_MATH__) || ((defined(__arm__) || defined(_M_ARM) || defined(__thumb__) ||              \
      defined(__aarch64__) || defined(_M_ARM64)) &&                             \
-    !defined(__ARM_FP)
+    !defined(__ARM_FP))
 #define __LIBC_SUPPORTS_MATH_ERREXCEPT 0
 #else
 #define __LIBC_SUPPORTS_MATH_ERREXCEPT 1