BaseTools/Scripts: Add sample makefile for use with RunMakefile.py

https://bugzilla.tianocore.org/show_bug.cgi?id=670

Add sample makefile that can be used to test RunMakefile.py
script and can also be used as a template to start a new
PREBUILD/POSTBUILD makefile.

This makefile contains TAB characters instead of spaces on
purpose to maximize compatibility with make utilities.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>

BaseTools/Scripts/RunMakefileSample.mak

@@ -0,0 +1,43 @@
+## @file
+# Sample makefile for PREBUILD or POSTBUILD action.
+#
+# Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
+# This program and the accompanying materials
+# are licensed and made available under the terms and conditions of the BSD License
+# which accompanies this distribution.  The full text of the license may be found at
+# http://opensource.org/licenses/bsd-license.php
+#
+# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+
+all: show
+	@echo $@
+genc: show
+	@echo $@
+genmake: show
+	@echo $@
+modules: show
+	@echo $@
+libraries: show
+	@echo $@
+fds: show
+	@echo $@
+clean: show
+	@echo $@
+cleanall: show
+	@echo $@
+cleanlib: show
+	@echo $@
+run: show
+	@echo $@
+
+show:
+	@echo WORKSPACE........ $(WORKSPACE)
+	@echo PACKAGES_PATH.... $(PACKAGES_PATH)
+	@echo ACTIVE_PLATFORM.. $(ACTIVE_PLATFORM)
+	@echo TARGET_ARCH...... $(TARGET_ARCH)
+	@echo TOOL_CHAIN_TAG... $(TOOL_CHAIN_TAG)
+	@echo CONF_DIRECTORY... $(CONF_DIRECTORY)
+	@echo TARGET........... $(TARGET)
+	@echo EXTRA_FLAGS...... $(EXTRA_FLAGS)