Fixed some compatibility problems with older clang versions

modules/juce_audio_processors/format_types/juce_VST3Headers.h

@@ -47,7 +47,9 @@
  #pragma clang diagnostic ignored "-Wdeprecated-declarations"
  #pragma clang diagnostic ignored "-Wextra-semi"
  #pragma clang diagnostic ignored "-Wmissing-braces"
- #pragma clang diagnostic ignored "-Wshadow-field"
+ #if __has_warning("-Wshadow-field")
+  #pragma clang diagnostic ignored "-Wshadow-field"
+ #endif
  #if __has_warning("-Wpragma-pack")
   #pragma clang diagnostic ignored "-Wpragma-pack"
  #endif

modules/juce_box2d/juce_box2d.h

@@ -57,7 +57,9 @@
 #ifdef JUCE_CLANG
  #pragma clang diagnostic push
  #pragma clang diagnostic ignored "-Wconversion"
- #pragma clang diagnostic ignored "-Wshadow-field"
+ #if __has_warning("-Wshadow-field")
+  #pragma clang diagnostic ignored "-Wshadow-field"
+ #endif
  #if __has_warning("-Wzero-as-null-pointer-constant")
   #pragma clang diagnostic ignored "-Wzero-as-null-pointer-constant"
  #endif