Add support for GNU GLOBAL.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/225183015

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20557 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

.gitignore

@@ -63,3 +63,4 @@ GTAGS
 GRTAGS
 GSYMS
 GPATH
+gtags.files

Makefile

@@ -409,7 +409,7 @@ native.clean:
 	rm -rf $(OUTDIR)/native
 	find $(OUTDIR) -regex '.*\(host\|target\)\.native\.mk' -delete
 
-clean: $(addsuffix .clean, $(ARCHES) $(ANDROID_ARCHES) $(NACL_ARCHES)) native.clean
+clean: $(addsuffix .clean, $(ARCHES) $(ANDROID_ARCHES) $(NACL_ARCHES)) native.clean gtags.clean
 
 # GYP file generation targets.
 OUT_MAKEFILES = $(addprefix $(OUTDIR)/Makefile.,$(BUILDS))
@@ -467,6 +467,16 @@ grokdump: ia32.release
 	@cat $(DUMP_FILE).tmpl > $(DUMP_FILE)
 	@$(OUTDIR)/ia32.release/d8 --dump-heap-constants >> $(DUMP_FILE)
 
+# Support for the GNU GLOBAL Source Code Tag System.
+gtags.files: $(GYPFILES) $(ENVFILE)
+	@find include src test -name '*.h' -o -name '*.cc' -o -name '*.c' > $@
+
+GTAGS GRTAGS GPATH: gtags.files
+	@GTAGSFORCECPP=yes gtags -i -q
+
+gtags.clean:
+	rm -f GTAGS GRTAGS GPATH gtags.files
+
 # Dependencies.
 # Remember to keep these in sync with the DEPS file.
 dependencies: