* Fix spelling/wording issues
* gitlab CI: add a basic build test
* Import reallocarray() from libX11 (originally from OpenBSD)
* Convert code to use Xmallocarray() & Xreallocarray()
* configure: Use AC_USE_SYSTEM_EXTENSIONS to set GNU_SOURCE & other defines
OBS-URL: https://build.opensuse.org/package/show/X11:XOrg/libfontenc?expand=0&rev=16