--with-valgrind=/path builds broken on master

[jsquyres]

The addition of the new hwloc component (v1.11.3) appears to have broken external valgrind builds.

Specifically, early in configure, hwloc1113 checks for <valgrind/valgrind.h> and fails to find it. Note that this is fine for hwloc -- it doesn't need Valgrind support.

However, if OMPI was configured with --with-valgrind=/location, then later in configure, then opal/mca/memchecker/valgrind/configure.m4 adds -I/location/include to $CPPFLAGS and then checks for <valgrind/valgrind.h>. However, Autoconf thinks it has already done this test -- and uses the cached result (i.e., that <valgrind/valgrind.h> wasn't found). I.e., the new $CPPFLAGS value is ignored.

I'm not sure what the correct fix is here.

[rhc54]

If hwloc doesn't need valgrind, then why does it include that header and check for it??

[jsquyres]

hwloc can use Valgrind, but it doesn't need it.

[bgoglin]

I committed your code with reworded comments and commit message. Thanks.