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>

 alpha does not have a __NR_creat

 http://bugs.gentoo.org/227275

 http://sourceware.org/bugzilla/show_bug.cgi?id=6650

 diff -durN glibc-2.13.orig/sysdeps/unix/sysv/linux/wordsize-64/creat64.c glibc-2.13/sysdeps/unix/sysv/linux/wordsize-64/creat64.c

 --- glibc-2.13.orig/sysdeps/unix/sysv/linux/wordsize-64/creat64.c	2007-11-10 20:34:26.000000000 +0100

 +++ glibc-2.13/sysdeps/unix/sysv/linux/wordsize-64/creat64.c	2009-11-13 00:50:51.000000000 +0100

 @@ -1 +1,5 @@

  /* Defined as alias for the syscall.  */

 +#include <sysdep.h>

 +#ifndef __NR_creat

 +#include "../../../../../io/creat64.c"

 +#endif