Remove protobuf-cpp-full-rtti from mainline

It used to be depended on by something on /product, but this
is no longer the case.

Bug: 119619080
Test: build downstream users of mainline_system
Change-Id: Iabe1dbb45499b25295f741a62336cb86e4565d60
diff --git a/target/product/mainline_system.mk b/target/product/mainline_system.mk
index 0ddc3db..ecd5691 100644
--- a/target/product/mainline_system.mk
+++ b/target/product/mainline_system.mk
@@ -81,7 +81,6 @@
     libminui \
     libnl \
     libprotobuf-cpp-full \
-    libprotobuf-cpp-full-rtti \
 
 PRODUCT_PACKAGES_DEBUG += \
     avbctl \