tools lib traceevent: Teach [ce]tags about libtraceeevent error codes

As we use a macro trick to sync each error codes with its description
string, teach [ce]tags to process them properly.

This patch modifies the libtraceevent's Makefile not a kernel one.

Suggested-by: Steven Rostedt <[e-mail]>
Signed-off-by: Namhyung Kim <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Cc: Frederic Weisbecker <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/traceevent/Makefile

···
 
 tags:	force
 	$(RM) tags
-	find . -name '*.[ch]' | xargs ctags --extra=+f --c-kinds=+px
+	find . -name '*.[ch]' | xargs ctags --extra=+f --c-kinds=+px \
+	--regex-c++='/_PE\(([^,)]*).*/PEVENT_ERRNO__\1/'
 
 TAGS:	force
 	$(RM) TAGS
-	find . -name '*.[ch]' | xargs etags
+	find . -name '*.[ch]' | xargs etags \
+	--regex='/_PE(\([^,)]*\).*/PEVENT_ERRNO__\1/'
 
 define do_install
 	$(print_install)				\