Add additional checks to enable/disable AUv3 support

modules/juce_audio_plugin_client/AU/juce_AUv3_Wrapper.mm

@@ -32,7 +32,7 @@
 #import <AVFoundation/AVFoundation.h>
 
 #if JUCE_MAC
- #if (! defined MAC_OS_X_VERSION_MIN_REQUIRED) || (MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_8)
+ #if (! defined MAC_OS_X_VERSION_MIN_REQUIRED) || (MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_11)
   #error AUv3 needs Deployment Target OS X 10.8 or higher to compile
  #endif
 #endif

modules/juce_audio_processors/format_types/juce_AudioUnitPluginFormat.mm

@@ -40,7 +40,9 @@
 #endif
 
 #ifndef JUCE_SUPPORTS_AUv3
- #if JUCE_COMPILER_SUPPORTS_VARIADIC_TEMPLATES && defined (MAC_OS_X_VERSION_MIN_REQUIRED) && (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_8) && __OBJC2__
+ #if JUCE_COMPILER_SUPPORTS_VARIADIC_TEMPLATES && __OBJC2__  \
+      &&  (defined (MAC_OS_X_VERSION_MIN_REQUIRED)    && (MAC_OS_X_VERSION_MIN_REQUIRED    >= MAC_OS_X_VERSION_10_11) \
+       ||  defined (__IPHONE_OS_VERSION_MIN_REQUIRED) && (__IPHONE_OS_VERSION_MIN_REQUIRED >= __IPHONE_9_0))
   #define JUCE_SUPPORTS_AUv3 1
  #else
   #define JUCE_SUPPORTS_AUv3 0