Macos xcode fixes (#6640)

changelog #osx remove all i386 specific macros from CoreOF xcconfig - allows Xcode to default to native arch

libs/openFrameworksCompiled/project/osx/CoreOF.xcconfig

@@ -1,12 +1,6 @@
-ARCHS = $(ARCHS_STANDARD_32_64_BIT)	// this allows you to select target architecture in dropdown menu
-VALID_ARCHS = x86_64
-
-ONLY_ACTIVE_ARCH = YES      // this makes sure not to build an universal binary
-
 //// define which C++ library is required to build, based on target architecture
-
-CLANG_CXX_LIBRARY[arch=x86_64] = libc++
-CLANG_CXX_LANGUAGE_STANDARD[arch=x86_64] = c++11
+CLANG_CXX_LIBRARY = libc++
+CLANG_CXX_LANGUAGE_STANDARD = c++11
 
 MACOSX_DEPLOYMENT_TARGET = 10.9