Pin platform/build to oreo-cts-dev.

Bug: 168629410
Change-Id: I7ed5edd1937e54f749f2248fd350e59224cec8c4
diff --git a/default.xml b/default.xml
index 1975802..df2a5b1 100644
--- a/default.xml
+++ b/default.xml
@@ -8,7 +8,7 @@
            remote="aosp"
            sync-j="4" />
 
-  <project path="build/make" name="platform/build" groups="pdk" >
+  <project path="build/make" name="platform/build" groups="pdk" revision="oreo-cts-dev" >
     <copyfile src="core/root.mk" dest="Makefile" />
     <linkfile src="CleanSpec.mk" dest="build/CleanSpec.mk" />
     <linkfile src="buildspec.mk.default" dest="build/buildspec.mk.default" />