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-2.7/glibc-ports-2.7.orig/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h	2007-06-06 19:27:04.000000000 +0200

 +++ glibc-2.7/glibc-ports-2.7/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h	2008-05-18 16:57:21.000000000 +0200

 @@ -73,6 +73,9 @@

  # define DOCARGS_5	DOCARGS_4

  # define UNDOCARGS_5	UNDOCARGS_4

 +# define DOCARGS_6    DOCARGS_5

 +# define UNDOCARGS_6  UNDOCARGS_5

 +

  # ifdef IS_IN_libpthread

  #  define CENABLE	bl PLTJMP(__pthread_enable_asynccancel)

  #  define CDISABLE	bl PLTJMP(__pthread_disable_asynccancel)