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>

# Menu for the native GDB

config GDB_NATIVE

    bool

    prompt "Native gdb"

    depends on ! BARE_METAL

    depends on ! BACKEND

    help

      Build and install a native gdb for the target, to run on the target.

if GDB_NATIVE

config GDB_NATIVE_STATIC

    bool

    prompt "Build a static native gdb"

    help

      In case you have trouble with dynamic loading of shared libraries,

      you will find that a static gdb comes in handy.

endif # GDB_NATIVE