Use CMAKE_OSX_SYSROOT and CMAKE_OSX_DEPLOYMENT_TARGET to set the Xcode
SDKROOT and MACOSX_DEPLOYMENT_TARGET build settings. This is necessary
because some versions of Xcode select a different compiler based on
these settings. We need to make sure the compiler identified during
language initialization matches what will be used for the actual build.
Since we do not need the information about the target architecture
we can use the PlatformName only to specify the this information.
This also removes setting of the MSVC_*_ARCHITECTURE_ID variable
which is not required, because this variable gets set by the
compiler detection code in CMAKE_DETERMINE_COMPILER_ID_CHECK().
The Microsoft linker is intelligent enough to detect the target
machine type depending on the input files. This allows us to
get the target architecture from the compiler instead of
maintaining the mapping to the platform name.
Add a dummy mainCRTStartup() function, since the linker searches for
it instead of main() and set the CMAKE_SYSTEM_* variables depending
on the MSVC_C_ARCHITECTURE_ID and CMAKE_VS_WINCE_VERSION variables.
If the TargetMachine isn't defined the linker will choose
the correct target depending on the input file. This helps
us later with additional compiler platforms for WinCE.
Configure a hand-generated Visual Studio project to build the compiler id
source file since we cannot run the compiler command-line tool directly.
Add a post-build command to print out the full path to the compiler tool.
Parse the full path to the compiler tool from the build output.
Configure a hand-generated Xcode project to build the compiler id source
file since we cannot run the compiler command-line tool directly. Add a
post-build shell script phase to print out the compiler toolset build
setting. Run xcodebuild to compile the identification binary. Parse
the full path to the compiler tool from the xcodebuild output.
