config: add keysymdef and xf86keysym as dependencies of ks_tables.h

This would cover the scenario where these headers file are updated,
for example, a new version is installed. Running 'make' again
on libxkbcommon should rebuild ks_tables.h.

Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>
Signed-off-by: Gaetan Nadon <memsize@videotron.ca>
diff --git a/src/Makefile.am b/src/Makefile.am
index 9a77ece..b9a12b9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -26,5 +26,5 @@
 BUILT_SOURCES = ks_tables.h
 CLEANFILES = $(BUILT_SOURCES)
 
-ks_tables.h: $(top_builddir)/makekeys/makekeys$(EXEEXT)
+ks_tables.h: $(top_builddir)/makekeys/makekeys$(EXEEXT) $(KEYSYMDEF_H) $(XF86KEYSYM_H)
 	$(AM_V_GEN)cat $(KEYSYMDEF_H) $(XF86KEYSYM_H) | $(top_builddir)/makekeys/makekeys$(EXEEXT) > $@