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>

 diff -durN gcc-4.3.2.orig/libgcc/config/sh/t-linux gcc-4.3.2/libgcc/config/sh/t-linux

 --- gcc-4.3.2.orig/libgcc/config/sh/t-linux	2009-03-07 11:42:38.000000000 +0100

 +++ gcc-4.3.2/libgcc/config/sh/t-linux	2009-03-07 11:03:39.000000000 +0100

 @@ -15,7 +15,7 @@

  	-Wl,--soname=@shlib_base_name@.so.1 \

  	-Wl,--version-script=@shlib_map_file@ \

  	-o @multilib_dir@/@shlib_base_name@.so.1.tmp @multilib_flags@ \

 -	@shlib_objs@ -lc && \

 +	@shlib_objs@ && \

  	rm -f @multilib_dir@/@shlib_base_name@.so && \

  	if [ -f @multilib_dir@/@shlib_base_name@.so.1 ]; then \

  	  mv -f @multilib_dir@/@shlib_base_name@.so.1 \