Question about substituting $(MAKE) and recursive makes.

[Kelley Cook]

For the GCC project, there are numberous places where we have something 
similar to

dep:
 $(MAKE) LANGUAGES="$(LANGUAGES)" BOOT_CFLAGS="$(BOOT_CFLAGS)" newstage

which proved to be prone to mistakes in maintenance of the Makefile.

So, I attempted to define a

REMAKE=$(MAKE) LANGUAGES="$(LANGUAGES)" BOOT_CFLAGS="$(BOOT_CFLAGS)"

and then replace those constructs with

dep:
 $(REMAKE) newstage

but any parallel build ended up being serialized once it recursed.

It was suggested to try

dep:
 +$(REMAKE) newstage

which does *seem* to work, but I cannot see where in the manual that 
this construct is supposed to allow parallel builds to work again.  From 
what I can tell the '+' should only affect '-n', '-t', and '-q'.  Though 
the 'MAKE' variable page does mention that the special variable 
'$(MAKE)' acts like it was specified with '+$(MAKE)'.

Can you please shed some light on this?  Is it valid, and if not is 
their a better way to do this.

Note that we don't wish to use export since we don't want to pass those 
flags to all the recursive makes, just most of them.

Kelley Cook