Fix clang warning: unknown warning group '-Wreserved-id-macro'

imgui_demo.cpp

@@ -30,7 +30,9 @@
 #pragma clang diagnostic ignored "-Wint-to-void-pointer-cast"   // warning : cast to 'void *' from smaller integer type 'int'
 #pragma clang diagnostic ignored "-Wformat-security"            // warning : warning: format string is not a string literal
 #pragma clang diagnostic ignored "-Wexit-time-destructors"      // warning : declaration requires an exit-time destructor       // exit-time destruction order is undefined. if MemFree() leads to users code that has been disabled before exit it might cause problems. ImGui coding style welcomes static/globals.
-#pragma clang diagnostic ignored "-Wreserved-id-macro"          // warning : macro name is a reserved identifier                // 
+#if __has_warning("-Wreserved-id-macro")
+#pragma clang diagnostic ignored "-Wreserved-id-macro"          // warning : macro name is a reserved identifier                //
+#endif
 #elif defined(__GNUC__)
 #pragma GCC diagnostic ignored "-Wint-to-pointer-cast"          // warning: cast to pointer from integer of different size
 #pragma GCC diagnostic ignored "-Wformat-security"              // warning : format string is not a string literal (potentially insecure)

imgui_draw.cpp

@@ -39,7 +39,9 @@
 #pragma clang diagnostic ignored "-Wfloat-equal"            // warning : comparing floating point with == or != is unsafe   // storing and comparing against same constants ok.
 #pragma clang diagnostic ignored "-Wglobal-constructors"    // warning : declaration requires a global destructor           // similar to above, not sure what the exact difference it.
 #pragma clang diagnostic ignored "-Wsign-conversion"        // warning : implicit conversion changes signedness             //
+#if __has_warning("-Wreserved-id-macro")
 #pragma clang diagnostic ignored "-Wreserved-id-macro"      // warning : macro name is a reserved identifier                //
+#endif
 #elif defined(__GNUC__)
 #pragma GCC diagnostic ignored "-Wunused-function"          // warning: 'xxxx' defined but not used
 #pragma GCC diagnostic ignored "-Wdouble-promotion"         // warning: implicit conversion from 'float' to 'double' when passing argument to function