Merge branch 'jc/test-lib-source-build-options-early'

Reorders t/test-lib.sh so that we dot-source GIT-BUILD-OPTIONS that records the shell and Perl the user told us to use with Git a lot early, so that test-lib.sh script itself can use "$PERL_PATH" in one of its early operations. * jc/test-lib-source-build-options-early: test-lib: reorder and include GIT-BUILD-OPTIONS a lot earlier