Add option to skip fetch external sources

Added option to check_build_sanity.py to skip running
fetch_sources.py. Allows to run multiple concurrent invocations
of check_build_sanity.py using the same source folder.

Components: Framework

Change-Id: I6289920860fb20287c405cefc0213c27f326857b
diff --git a/scripts/check_build_sanity.py b/scripts/check_build_sanity.py
index 88500a4..6f05f33 100644
--- a/scripts/check_build_sanity.py
+++ b/scripts/check_build_sanity.py
@@ -135,10 +135,6 @@
 		else:
 			print "Skip: %s" % step.getName()
 
-def runRecipe (steps):
-	allSteps = PREREQUISITES + steps + POST_CHECKS
-	runSteps(allSteps)
-
 COMMON_GCC_CFLAGS	= ["-Werror"]
 COMMON_CLANG_CFLAGS	= COMMON_GCC_CFLAGS + ["-Wno-error=unused-command-line-argument"]
 GCC_32BIT_CFLAGS	= COMMON_GCC_CFLAGS + ["-m32"]
@@ -247,6 +243,11 @@
 						dest="dumpRecipes",
 						action="store_true",
 						help="Print out recipes that have any available actions")
+	parser.add_argument("--skip-prerequisites",
+						dest="skipPrerequisites",
+						action="store_true",
+						help="Skip external dependency fetch")
+
 	return parser.parse_args()
 
 if __name__ == "__main__":
@@ -265,6 +266,7 @@
 
 		print "Running %s" % name
 
-		runRecipe(steps)
+		allSteps = (PREREQUISITES if (args.skipPrerequisites == False) else []) + steps + POST_CHECKS
+		runSteps(allSteps)
 
 		print "All steps completed successfully"