This partially reverts r262482, at it broke canadian builds.

2018-08-03  Pierre-Marie de Rodat  <derodat@adacore.com>

gcc/ada/

	Reverts
	2018-07-06  Jim Wilson  <jimw@sifive.com>

	* Make-generated.in (treeprs.ads): Use $(GNATMAKE) instead of gnatmake.
	(einfo.h, sinfo.h, stamp-snames, stamp-nmake): Likewise.
	* gcc-interface/Makefile.in (xoscons): Likewise.

From-SVN: r263291