Fix syntax error in METADATA file. am: 2a8dc2a147

Original change: https://android-review.googlesource.com/c/platform/prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/+/2254838

Change-Id: I74ca87b2f07e926f2bcd90872a7e119e415713cc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>