Only write appcompat properties if flag is defined

Only writes the appcompat properties if the
WRITE_APPCOMPAT_OVERRIDE_SYSTEM_PROPERTIES cflag is defined

Fixes: 331307495
Test: manual
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f04f6bae4314e01111045ba231010ba7067477a0)
Merged-In: Ie99b5027a9704c0f4f7fe4d3a6a6cf49f4bb8176
Change-Id: Ie99b5027a9704c0f4f7fe4d3a6a6cf49f4bb8176
2 files changed