modula2: Add dependencies for generated sources

This patch adds rules and dependencies for the automatically
generated grammar sources.  Bootstrapped using make -j 160.

gcc/m2/ChangeLog:

	* Make-lang.in (m2/gm2-compiler-boot/P0SyntaxCheck.c):
	New rule.
	(m2/gm2-compiler-boot/P0SyntaxCheck.o): Ditto.
	(m2/gm2-compiler-boot/P1Build.c): Ditto.
	(m2/gm2-compiler-boot/P1Build.o): Ditto.
	(m2/gm2-compiler-boot/P2Build.c): Ditto.
	(m2/gm2-compiler-boot/P2Build.o): Ditto.
	(m2/gm2-compiler-boot/P3Build.c): Ditto.
	(m2/gm2-compiler-boot/P3Build.o): Ditto.
	(m2/gm2-compiler-boot/PCBuild.c): Ditto.
	(m2/gm2-compiler-boot/PCBuild.o): Ditto.
	(m2/gm2-compiler-boot/PHBuild.c): Ditto.
	(m2/gm2-compiler-boot/PHBuild.o): Ditto.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>