2018-05-30  Arnaud Charlet  <charlet@adacore.com>

gcc/ada/

	* gcc-interface/Makefile.in: Move special flags for Ada runtime files
	from here...
	* Makefile.rtl: ... to here.  Update comments.  Protect call to
	"GCC_FOR_TARGET" in case target_os isn't defined.

From-SVN: r260922