get-rusage-as, pthread_sigmask tests: Fix -fsanitize=thread findings. * lib/get-rusage-as.c (get_rusage_as): When compiled by "gcc -fsanitize=thread", don't try get_rusage_as_via_setrlimit. * tests/test-pthread_sigmask2.c (main): Clean up the killer_thread before exiting.

# See lib/git-merge-changelog.c for making this useful.
ChangeLog	merge=merge-changelog

# Run this to make 'git diff' on texinfo files give nicer hunk context:
#   git config diff.texinfo.funcname '^@node[	 ][	 ]*\\([^,][^,]*\\)'
*.texi* diff=texinfo