ozone: gbm: Default use_system_minigbm=1 to mitigate build breaks

The chrome-sdk needs to update with the flag to avoid breakage.
This CL can be reverted when the chrome-sdk updates with the
new use_system_minigbm setting in GYP_DEFINES.

TBR=dnicoara (build break)
NOTRY=true

Review URL: https://codereview.chromium.org/1344263002 .

Cr-Original-Commit-Position: refs/heads/master@{#349041}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 0e8f0106e7e01cee911dd2b34c263c01788e7186

common.gypi

@@ -2378,7 +2378,6 @@
 
         # Build all platforms whose deps are in install-build-deps.sh.
         # Only these platforms will be compile tested by buildbots.
-        'ozone_platform_gbm%': 1,
         'ozone_platform_test%': 1,
         'ozone_platform_egltest%': 1,
       }],