Make build_shaderc.py blow away output dir and allow build_type arg to contain either Debug or Relea

tools/build_shaderc.py

 #!/usr/bin/python
 
 # Copyright 2016 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 
 """
 Script to build the shaderc library.
@@ skipping 18 matching lines @@
       'Directory for cmake build')
   parser.add_argument('-p', '--project_type', required=True, help=
       'Project type to use. Must be "ninja", "MSVS2013", or "MSVS2015"')
   args = parser.parse_args()
 
   args.src_dir = os.path.abspath(args.src_dir)
   args.output_dir = os.path.abspath(args.output_dir)
 
   if not os.path.isdir(args.src_dir):
     sys.exit(args.src_dir + ' is not a directory.')
-    
-  if args.build_type != 'Debug' and args.build_type != 'Release':
-    sys.exit('Invalid build type: ' + args.build_type);
+
+  if 'Release' in args.build_type:
+    args.build_type = "Release"
+  elif 'Debug' in args.build_type:
+    args.build_type = "Debug"
+  else:
+    args.exit('Invalid build type: ' + args.build_type);
 
   if args.arch_type == 'x86':
     vs_arch = ''
   elif args.arch_type == 'x86_64':
     vs_arch = ' Win64'
   else:
     sys.exit('Invalid arch type: ' + args.arch_type);
 
   if args.project_type == 'ninja':
     generator = 'Ninja'
   elif args.project_type == 'MSVS2013':
     generator = 'Visual Studio 12 2013' + vs_arch
   elif args.project_type == "MSVS2015":
     generator = 'Visual Studio 14 2015' + vs_arch
   else:
     sys.exit('Invalid project type: ' + args.project_type);
 
-  if not os.path.isdir(args.output_dir):
-    try:
-      os.makedirs(args.output_dir)
-    except os.error:
-      sys.exit('Error creating output dir ' + args.output_dir)
+  if os.path.isdir(args.output_dir):
+    shutil.rmtree(args.output_dir)
+
+  try:
+    os.makedirs(args.output_dir)
+  except os.error:
+    sys.exit('Error creating output dir ' + args.output_dir)
 
   try:
     build_type_arg='-DCMAKE_BUILD_TYPE=' + args.build_type
     subprocess.check_call(['cmake', '-G', generator,
         '-DSPIRV_SKIP_EXECUTABLES=ON', '-DSHADERC_ENABLE_SHARED_CRT=ON',
         args.src_dir, build_type_arg], cwd=args.output_dir)
   except subprocess.CalledProcessError as error:
     sys.exit('Error (ret code: {code}) calling "{cmd}" in {dir}'.format(
         code = error.returncode, cmd = error.cmd, dir = args.src_dir))
 
   try:
     subprocess.check_call(['cmake', '--build', args.output_dir, '--config',
         args.build_type], cwd=args.output_dir)
   except subprocess.CalledProcessError as error:
     sys.exit('Error (ret code: {code}) calling "{cmd}" in {dir}'.format(
         code = error.returncode, cmd = error.cmd, dir = args.src_dir))
 
 if __name__ == '__main__':
   main()