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 -ur uClibc-0.9.29/libc/inet/resolv.c uClibc-0.9.29-patched/libc/inet/resolv.c

 --- uClibc-0.9.29/libc/inet/resolv.c	2007-04-23 12:01:05.000000000 -0500

 +++ uClibc-0.9.29-patched/libc/inet/resolv.c	2007-05-09 18:05:33.563404419 -0500

 @@ -1700,7 +1700,7 @@

  int gethostent_r(struct hostent *result_buf, char *buf, size_t buflen,

  	struct hostent **result, int *h_errnop)

  {

 -    int ret;

 +    int ret = HOST_NOT_FOUND;

      __UCLIBC_MUTEX_LOCK(mylock);

      if (__gethostent_fp == NULL) {