Export OVERRIDE_RS_DRIVER to soong

Bug: 37035983
Test: examine RS cflags
Change-Id: I0c1cc54f3f7f860895322d2825c7168c93a84ef5
Merged-In: I0c1cc54f3f7f860895322d2825c7168c93a84ef5
(cherry picked from commit 7932f9bc5ddf6fa2465e78a364274b40e1243251)
1 file changed