Win SDK: fix missing platforms-tools/dx.bat

In the new windows.atree, the batch file was missing the .bat extension.
This prevents the SDK Manager from recognizing platform-tools.

Change-Id: I885b748f9ce7f6ceeb9f7b9c35ca38f7b8029f55
diff --git a/build/sdk-windows-x86.atree b/build/sdk-windows-x86.atree
index 7e974bc..68105a2 100644
--- a/build/sdk-windows-x86.atree
+++ b/build/sdk-windows-x86.atree
@@ -38,7 +38,7 @@
 bin/aidl.exe                            strip platform-tools/aidl.exe
 
 rm platform-tools/dx
-dalvik/dx/etc/dx.bat                          platform-tools/dx
+dalvik/dx/etc/dx.bat                          platform-tools/dx.bat
 
 rm platform-tools/dexdump
 bin/dexdump.exe                         strip platform-tools/dexdump.exe