comparison of integers of different signs: 'char' and 'kmp_uint64'

Jonathan,
       Is this warning serious?

/sw/src/fink.build/llvm37-3.7.0-100/llvm-3.7.0.src/projects/openmp/runtime/src/kmp_wait_release.h:488:79:
warning: comparison of integers of different signs: 'char' and
'kmp_uint64'

      (aka 'unsigned long long') [-Wsign-compare]

    bool done_check_val(kmp_uint64 old_loc) { return
byteref(&old_loc,offset) == checker; }

~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~
we also have a similar one at...

/sw/src/fink.build/llvm37-3.7.0-100/llvm-3.7.0.src/projects/openmp/runtime/src/z_Linux_util.c:873:25:
warning: comparison of integers of different signs: 'long' and
'unsigned long long' [-Wsign-compare]
        if (now.tv_nsec >= NSEC_PER_SEC) {
            ~~~~~~~~~~~ ^ ~~~~~~~~~~~~

   Jack