envsetup.sh: Fix handling of emulator prebuilts path.

Due to a bad previous merge, everytime 'lunch' is called, a new
instance of prebuilts/android-emulator/<system>/ will be added
to your PATH.

This patch fixes the issue by removing the duplicate code that
should have been removed during the merge. Note that android-emulator
is still being added once to the PATH by code that appears before
in the script.

BUG=17524154

Change-Id: Iaa03159b0c81b15ef4c7c420e2f76e0a48aba789
diff --git a/envsetup.sh b/envsetup.sh
index 2c74b2d..1798635 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -206,24 +206,6 @@
     unset ANDROID_HOST_OUT
     export ANDROID_HOST_OUT=$(get_abs_build_var HOST_OUT)
 
-    # If prebuilts/android-emulator/<system>/ exists, prepend it to our PATH
-    # to ensure that the corresponding 'emulator' binaries are used.
-    case $(uname -s) in
-        Darwin)
-            ANDROID_EMULATOR_PREBUILTS=$T/prebuilts/android-emulator/darwin-x86_64
-            ;;
-        Linux)
-            ANDROID_EMULATOR_PREBUILTS=$T/prebuilts/android-emulator/linux-x86_64
-            ;;
-        *)
-            ANDROID_EMULATOR_PREBUILTS=
-            ;;
-    esac
-    if [ -n "$ANDROID_EMULATOR_PREBUILTS" -a -d "$ANDROID_EMULATOR_PREBUILTS" ]; then
-        PATH=$ANDROID_EMULATOR_PREBUILTS:$PATH
-        export ANDROID_EMULATOR_PREBUILTS
-    fi
-
     # needed for building linux on MacOS
     # TODO: fix the path
     #export HOST_EXTRACFLAGS="-I "$T/system/kernel_headers/host_include