git-merge-changelog, gen-uni-tables: Use str_startswith. * lib/git-merge-changelog.c (main): Use str_startswith. * lib/gen-uni-tables.c (output_predicate, is_property_composite, is_nonspacing): Likewise. * modules/git-merge-changelog (Depends-on): Add str_startswith. * modules/gen-uni-tables (Depends-on): Likewise.