more Linux clang compile failures

src/hotspot/os_cpu/bsd_x86/os_bsd_x86.cpp got fixed in

8181503: Can't compile hotspot with c++11
Summary: Fixed 5 unique c++14 compiler issues
Reviewed-by: coleenp, dholmes, kbarrett

but those same fixes need to be applied to the Linux equivalent.

Here's another one:

src/hotspot/share/utilities/debug.cpp:718: error: comparison between pointer and integer ('void *' and 'bool')
  if (memcpy(&g_stored_assertion_context, context, sizeof(ucontext_t)) == false) {
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~