Makefile.in: Simplify recursive make callings.

[Zack Weinberg]

Kelley Cook <kcook34@ford.com> writes:

> This patch simply defines a new variable within GCC's Makefile.in
>
> REMAKE=$(MAKE) LANGUAGES="$(LANGUAGES)" BOOT_CFLAGS="$(BOOT_CFLAGS)"
>
> and replaces all of those calls with $(REMAKE).

Make handles commands with $(MAKE) in them specially.  It is not clear
to me that this still works if the $(MAKE) comes from a variable.
Therefore I'd prefer that you did this

REMAKEARGS= LANGUAGES="$(LANGUAGES)" BOOT_CFLAGS="$(BOOT_CFLAGS)"
...

foo:
	$(MAKE) $(REMAKEARGS) ...

even though that's more verbose.  Or else find out for sure that your
original code is safe.

zw