Add clang.exe to Windows SDK build.

Bug: 22044739

This is needed as part of the NDK itself, now that we are shipping the
platform Clang as the one true Clang. It can be built by doing:

make winsdk-tools

Change-Id: I3363f46b5dcc52258aa92b42b5a92a96bf868e73

build/product_sdk.mk

@@ -33,6 +33,7 @@ PRODUCT_PACKAGES += \
 	zipalign \
 	bcc_compat \
 	bios.bin \
+	clang \
 	commons-compress-1.0 \
 	dexdump \
 	dmtracedump \

build/tools/windows_sdk.mk

@@ -34,6 +34,7 @@ WIN_TARGETS := \
 	aapt adb aidl \
 	aprotoc \
 	bcc_compat \
+	clang \
 	etc1tool \
 	dexdump dmtracedump \
 	fastboot \