rc.exe doesn't support /showIncludes.
Because .rc files also #include stuff we can
misuse cl.exe to get the included files.
Done one the fly by cmcldeps.
cmcldeps wraps cl and adds /showInclude before calling cl.
It parses the output of cl for used headers, drops system
headers and writes them to a GCC like dependency file.
cmcldeps uses ATM ninja code for process handling,
but could be ported later to SystemTools.
TODO: Why needs ninja multiple calls in the BuildDepends test?
