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>

 --- glibc-2.6/sysdeps/unix/sysv/linux/kernel-features.h	2006-07-29 07:43:27.000000000 +0300

 +++ glibc-2.6/sysdeps/unix/sysv/linux/kernel-features.h.new	2008-07-26 08:45:06.000000000 +0300

 @@ -445,7 +445,7 @@

  /* The *at syscalls were introduced just after 2.6.16-rc1.  Due to the way the

     kernel versions are advertised we can only rely on 2.6.17 to have

     the code.  */

 -#if __LINUX_KERNEL_VERSION >= 0x020611

 +#if __LINUX_KERNEL_VERSION >= 0x020611 && !defined __alpha__

  # define __ASSUME_ATFCTS	1

  #endif