xfd 1.1.4

• gitlab CI: add a basic build test
• Build xz tarballs instead of bzip2
• Use _CONST_X_STRING to make libXt declare String as const char *
• Fix warning: missing initializer for field ‘extension’ of ‘SimpleClassPart'
• Variable scope reductions as recommended by cppcheck
• Mark usage() as _X_NORETURN _X_COLD
• gitlab CI: stop requiring Signed-off-by in commits
• Handle -Wextra-semi-stmt warnings from clang
• Tag unused arguments to callback functions as _X_UNUSED