Revert^2 "Explicitly include libgui as a shared library in libgui_test."

This reverts commit d6198bed.

Reason for revert: Removed flag defines from Android.bp that caused linker errors.  Verified libgui_test behaves identically with and without this revert on cf_x86_64_auto-next-userdebug

Change-Id: Ibbbd201253fa09c18491bffca0b540c2c13df8d3