comptools: do not force build of make-3.81 unless really needed

On systems with make-3.82, we forcibly force the build and the use
of make-3.81

But some newer tools break when building with make-3.81. For example,
eglibc-3.18 breaks.

Introduce a new blind options that tools may select if they require
make-3.81. If the system does not have make-3.81, and this option is
selected, then we force the build of make-3.81. Otherwise, we leave
it to the user to decide on his own.

Note that no component selects this option for now. It will come in
later patches as we find them.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 Original patch from Gentoo.

 -= BEGIN original header =-

 -= END original header =-

 diff -durN uClibc-0.9.30.orig/Rules.mak uClibc-0.9.30/Rules.mak

 --- uClibc-0.9.30.orig/Rules.mak	2008-11-12 13:24:16.000000000 +0100

 +++ uClibc-0.9.30/Rules.mak	2009-02-07 09:57:59.000000000 +0100

 @@ -502,6 +502,7 @@

  endif

  CFLAGS += $(call check_gcc,-std=gnu99,)

 +CFLAGS += $(call check_gcc,-fgnu89-inline,)

  LDFLAGS_NOSTRIP:=$(CPU_LDFLAGS-y) -Wl,-shared \

  	-Wl,--warn-common -Wl,--warn-once -Wl,-z,combreloc