xkbcomp/parser: enable Bison detailed syntax error It's not much, but instead of xkbcommon: ERROR: [XKB-769] (unknown file):5:25: syntax error we get xkbcommon: ERROR: [XKB-769] (unknown file):5:25: syntax error, unexpected +, expecting INTEGER which is at least a little helpful. Signed-off-by: Ran Benita <ran@unusedvar.com>