AX_VALGRIND_CHECK for non-GNU make

[Reini Urban]

ax_valgrind_check.m4 creates a GNUmakefile-only snippet.
make clean and make check-valgrind will fail.

See also https://github.com/rurban/safeclib/issues/26

The fix is analog to the AX_CODE_COVERAGE patch, but this is trickier.
Some variables need to be expanded by make at run-time, and cannot be handled
by autoconf/automake: VALGRIND_SUPPRESSIONS_FILES

At https://github.com/rurban/autoconf-archive/commits/valgrind I have the 
following patch:

    Changed to always use LIBTOOL (could be improved by an autoconf check).
    Changed to allow only a single VALGRIND_SUPPRESSIONS_FILE file.
    False valgrind_v_use_0 display on BSD make $(patsubst) - beauty only.

    Works now also with other makes.

    To get back the old features (see above), is to add a new
    AX_VALGRIND_CHECK_GNU.

So what should we do? Add the extended old version as AX_VALGRIND_CHECK_GNU?
Somebody wants to improve the libtool check, so that it works without libtool 
also?
Ditto for the USE $tool message.

Reini Urban
address@hidden