Fix Windows build

Change-Id: I8769bafba199b9258c610e51b58e454fe10a75e6


[ROCm/hip commit: 36ecdf9c3a]

projects/hip/rocclr/hip_platform.cpp

@@ -686,11 +686,19 @@ static inline std::uint32_t __convert_float_to_half(float a) noexcept {
   return s | v;
 }
 
-extern "C" __attribute__((weak)) float  __gnu_h2f_ieee(unsigned short h){
+extern "C"
+#if !defined(_MSC_VER)
+__attribute__((weak))
+#endif
+float  __gnu_h2f_ieee(unsigned short h){
   return __convert_half_to_float((std::uint32_t) h);
 }
 
-extern "C" __attribute__((weak)) unsigned short  __gnu_f2h_ieee(float f){
+extern "C"
+#if !defined(_MSC_VER)
+__attribute__((weak))
+#endif
+unsigned short  __gnu_f2h_ieee(float f){
   return (unsigned short)__convert_float_to_half(f);
 }