PR modula2/116378 m2 bootstrap fails on x86_64-darwin

PR modula2/116378 m2 bootstrap fails on x86_64-darwin

This patch fixes m2 bootstrap failure on x86_64-darwin.  libc_open
is defined with three parameters the last of which is an int for
portability (rather than a vararg).  This avoids portability
problems by promoting mode_t to an int.  In the future it could
be tidied up by using the m2 optarg extension.

gcc/m2/ChangeLog:

	PR modula2/116378
	* gm2-libs-iso/TermFile.mod (termOpen): Add third argument
	for open.
	* gm2-libs/libc.def (open): Remove vararg and use INTEGER for
	mode parameter three.
	* mc-boot-ch/Glibc.c (tracedb_open): Replace mode_t with int.
	(libc_open): Rewrite without varargs.
	* mc-boot/Glibc.h (libc_open): Replace varargs with int mode.
	* pge-boot/Glibc.cc (libc_open): Rewrite.
	* pge-boot/Glibc.h (libc_open): Replace varargs with int mode.

gcc/testsuite/ChangeLog:

	PR modula2/116378
	* gm2/extensions/run/pass/testopen.mod: Add third argument
	for open.
	* gm2/isolib/run/pass/openlibc.mod: Ditto.
	* gm2/pim/run/pass/testaddr3.mod: Ditto.

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