PR modula2/112825: modula2 builds target objects as part of all-gcc

PR modula2/112825: modula2 builds target objects as part of all-gcc

This patch fixes the PR modula2/112825 which fails if the target
assembler is not present on the host.  This can be seen if the
build invokes make all-gcc.  m2 should not attempt to generate
target libraries when performing make all-gcc.

Prior to this patch it generated build/gcc/m2/gm2-libs/SYSTSEM.def
using the script gcc/m2/tools-src/makeSystem (and gm2 -c).
makeSystem should exec gm2 -S instead (and other flags)
to generate the list of target data types without requiring any
target tools.  The target types emitted are textually converted
into SYSTEM.def.

gcc/m2/ChangeLog:

	PR modula2/112825
	* tools-src/makeSystem: Change all occurrences of -c to -S.

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