cpupower: Add 'help' target to the main Makefile

Make "cpupower" building process more user friendly by adding 'help'
target to the main makefile. This target describes various build
and cleaning options available to the user.

Signed-off-by: Roman Storozhenko <romeusmeister@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: Romeus

tools/power/cpupower/Makefile

@@ -332,4 +332,39 @@ uninstall:
 		rm -f $(DESTDIR)${localedir}/$$HLANG/LC_MESSAGES/cpupower.mo; \
 	  done;
 
-.PHONY: all utils libcpupower update-po create-gmo install-lib install-tools install-man install-gmo install uninstall clean
+help:
+	@echo  'Building targets:'
+	@echo  '  all		  - Default target. Could be omitted. Put build artifacts'
+	@echo  '                    to "O" cmdline option dir (default: current dir)'
+	@echo  '  install	  - Install previously built project files from the output'
+	@echo  '                    dir defined by "O" cmdline option (default: current dir)'
+	@echo  '                    to the install dir  defined by "DESTDIR" cmdline or'
+	@echo  '                    Makefile config block option (default: "")'
+	@echo  '  install-lib	  - Install previously built library binary from the output'
+	@echo  '                    dir defined by "O" cmdline option (default: current dir)'
+	@echo  '                    and library headers from "lib/" for userspace to the install'
+	@echo  '                    dir  defined by "DESTDIR" cmdline (default: "")'
+	@echo  '  install-tools	  - Install previously built "cpupower" util from the output'
+	@echo  '                    dir defined by "O" cmdline option (default: current dir) and'
+	@echo  '                    "cpupower-completion.sh" script from the src dir to the'
+	@echo  '                    install dir  defined by "DESTDIR" cmdline or Makefile'
+	@echo  '                    config block option (default: "")'
+	@echo  '  install-man	  - Install man pages from the "man" src subdir to the'
+	@echo  '                    install dir  defined by "DESTDIR" cmdline or Makefile'
+	@echo  '                    config block option (default: "")'
+	@echo  '  install-gmo	  - Install previously built language files from the output'
+	@echo  '                    dir defined by "O" cmdline option (default: current dir)'
+	@echo  '                    to the install dir defined by "DESTDIR" cmdline or Makefile'
+	@echo  '                    config block option (default: "")'
+	@echo  '  install-bench	  - Install previously built "cpufreq-bench" util files from the'
+	@echo  '                    output dir defined by "O" cmdline option (default: current dir)'
+	@echo  '                    to the install dir  defined by "DESTDIR" cmdline or Makefile'
+	@echo  '                    config block option (default: "")'
+	@echo  ''
+	@echo  'Cleaning targets:'
+	@echo  '  clean		  - Clean build artifacts from the dir defined by "O" cmdline'
+	@echo  '                    option (default: current dir)'
+	@echo  '  uninstall	  - Remove previously installed files from the dir defined by "DESTDIR"'
+	@echo  '                    cmdline or Makefile config block option (default: "")'
+
+.PHONY: all utils libcpupower update-po create-gmo install-lib install-tools install-man install-gmo install uninstall clean help