Extend the change from commit dfaf55fbfd (Xcode: add extra
'$(inherited)' entries using InheritBuildSettingAttribute, 2021-05-03,
v3.21.0-rc1~182^2) to cover Swift flags and compilation conditions,
allowing CocoaPods and CMake to interoperate when used in the same
project.
These have been added to:
GCC_PREPROCESSOR_DEFINITIONS
OTHER_CFLAGS
OTHER_LDFLAGS
This is to allow Cocoapods to work correctly as it uses xcconfig files to alter build settings in Xcode, and requires these build settings to inherit from their parent, not overwrite.