Export OVERRIDE_RS_DRIVER to soong

Bug: 37035983
Test: examine RS cflags
Change-Id: I0c1cc54f3f7f860895322d2825c7168c93a84ef5
Merged-In: I0c1cc54f3f7f860895322d2825c7168c93a84ef5
(cherry picked from commit 7932f9bc5ddf6fa2465e78a364274b40e1243251)
diff --git a/core/soong_config.mk b/core/soong_config.mk
index 2157ed5..a075c96 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -67,6 +67,7 @@
 	echo '    "Safestack": $(if $(filter true,$(USE_SAFESTACK)),true,false),'; \
 	echo '    "EnableCFI": $(if $(filter true,$(ENABLE_CFI)),true,false),'; \
 	echo '    "Treble": $(if $(filter true,$(PRODUCT_FULL_TREBLE)),true,false),'; \
+	echo '    "Override_rs_driver": "$(OVERRIDE_RS_DRIVER)",'; \
 	echo ''; \
 	echo '    "ArtUseReadBarrier": $(if $(filter false,$(PRODUCT_ART_USE_READ_BARRIER)),false,true),'; \
 	echo ''; \