Put prebuilt emulator path after host output

So that built emulator is used instead of prebuilt one when
BUILD_EMULATOR=true.

Change-Id: I67dfbfc2c3bf9bf051e56de425caa07b08d4b2e4
diff --git a/envsetup.sh b/envsetup.sh
index d026466..e4e2ece 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -186,7 +186,7 @@
             ;;
     esac
     if [ -n "$ANDROID_EMULATOR_PREBUILTS" -a -d "$ANDROID_EMULATOR_PREBUILTS" ]; then
-        ANDROID_BUILD_PATHS=$ANDROID_EMULATOR_PREBUILTS:$ANDROID_BUILD_PATHS
+        ANDROID_BUILD_PATHS=$ANDROID_BUILD_PATHS:$ANDROID_EMULATOR_PREBUILTS
         export ANDROID_EMULATOR_PREBUILTS
     fi