[winpr,file] mark winpr_fopen with WINPR_ATTR_MALLOC

enable allocator/deallocator checks for FILE* created by this function

winpr/include/winpr/file.h

@@ -550,6 +550,7 @@ extern "C"
 	WINPR_API int GetNamePipeFileDescriptor(HANDLE hNamedPipe);
 	WINPR_API HANDLE GetFileHandleForFileDescriptor(int fd);
 
+	WINPR_ATTR_MALLOC(fclose, 1)
 	WINPR_API FILE* winpr_fopen(const char* path, const char* mode);
 
 #ifdef __cplusplus