Merge branch 'cb/grep-fallback-failing-jit'

Merge branch 'cb/grep-fallback-failing-jit'

In an environment where dynamically generated code is prohibited to
run (e.g. SELinux), failure to JIT pcre patterns is expected.  Fall
back to interpreted execution in such a case.

* cb/grep-fallback-failing-jit:
  grep: fall back to interpreter if JIT memory allocation fails