cpupower: add checks for xgettext and msgfmt

Check whether xgettext and msgfmt are available on the system before
attempting to generate GNU gettext Language Translations.
In case of missing dependency, generate error message directing user
to install the necessary package.

Tested-by: John B. Wyatt IV <jwyatt@redhat.com>
Tested-by: John B. Wyatt IV <sageofredondo@gmail.com>
Suggested-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Siddharth Menon <simeddon@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/power/cpupower/Makefile

@@ -218,17 +218,28 @@ else
 endif
 	$(QUIET) $(STRIPCMD) $@
 
+ifeq (, $(shell which xgettext))
+$(warning "Install xgettext to extract translatable strings.")
+else
 $(OUTPUT)po/$(PACKAGE).pot: $(UTIL_SRC)
 	$(ECHO) "  GETTEXT " $@
 	$(QUIET) xgettext --default-domain=$(PACKAGE) --add-comments \
 		--keyword=_ --keyword=N_ $(UTIL_SRC) -p $(@D) -o $(@F)
+endif
 
+ifeq (, $(shell which msgfmt))
+$(warning "Install msgfmt to generate binary message catalogs.")
+else
 $(OUTPUT)po/%.gmo: po/%.po
 	$(ECHO) "  MSGFMT  " $@
 	$(QUIET) msgfmt -o $@ po/$*.po
+endif
 
 create-gmo: ${GMO_FILES}
 
+ifeq (, $(shell which msgmerge))
+$(warning "Install msgmerge to merge translations.")
+else
 update-po: $(OUTPUT)po/$(PACKAGE).pot
 	$(ECHO) "  MSGMRG  " $@
 	$(QUIET) @for HLANG in $(LANGUAGES); do \
@@ -241,6 +252,7 @@ update-po: $(OUTPUT)po/$(PACKAGE).pot
 			rm -f $(OUTPUT)po/$$HLANG.new.po; \
 		fi; \
 	done;
+endif
 
 compile-bench: $(OUTPUT)libcpupower.so.$(LIB_MAJ)
 	@V=$(V) confdir=$(confdir) $(MAKE) -C bench O=$(OUTPUT)