Enable building sdk/avdlauncher in the Win SDK.

Required by Change-Id Ic651e3c3 in sdk.git

Change-Id: I97f389d052ba9abf1c40547abbc6d7c164bdf405
diff --git a/core/main.mk b/core/main.mk
index 1f03355..6841b36 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -415,6 +415,7 @@
 	external/zlib \
 	frameworks/base \
 	frameworks/compile \
+	sdk/avdlauncher \
 	sdk/emulator/mksdcard \
 	sdk/sdklauncher \
 	system/core/adb \