Add suggestion from @petrhoesk

Author: saturn691

libc/include/__llvm-libc-common.h

@@ -48,7 +48,11 @@
 #endif
 
 #undef _Returns_twice
+#if __cplusplus >= 201103L
 #define _Returns_twice [[gnu::returns_twice]]
+#else
+#define _Returns_twice __attribute__((returns_twice))
+#endif
 
 // This macro serves as a generic cast implementation for use in both C and C++,
 // similar to `__BIONIC_CAST` in Android.