complibs/cloog: create missing m4 dir

Because we now patch configure.in and configure, the Makefile quicks
in a re-build rule as the source files are now more recent than the
bundled generated files, and that fails because the m4 directory
is missing, although on some systems where aclocal is not installed,
the re-build rule does nothing (except a warning).

Always create tht directory.

Reported-by: Per Arnold Blaasmo <per-arnold.blaasmo@atmel.com>
[Also thanks to Thomas De Schampheleire <patrickdepinguin@gmail.com>
for some digging works on this issue]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 diff -durN gcc-3.4.6.orig/gcc/config/rs6000/linux-unwind.h gcc-3.4.6/gcc/config/rs6000/linux-unwind.h

 --- gcc-3.4.6.orig/gcc/config/rs6000/linux-unwind.h	2005-03-17 11:41:18.000000000 +0100

 +++ gcc-3.4.6/gcc/config/rs6000/linux-unwind.h	2007-08-15 23:07:00.000000000 +0200

 @@ -32,6 +32,7 @@

     these structs elsewhere;  Many fields are missing, particularly

     from the end of the structures.  */

 +#ifndef inhibit_libc

  struct gcc_vregs

  {

    __attribute__ ((vector_size (16))) int vr[32];

 @@ -320,3 +321,4 @@

  									\

      goto SUCCESS;							\

    } while (0)

 +#endif