firewalld: Disable RTTI

There is no longer a reliance on RTTI in libbrillo, so disable RTTI
in the rest of Brillo codebase.

Bug: 26292405
Change-Id: I9ef4ac224141dcabb69f79e076286ee711ad0b00
diff --git a/Android.mk b/Android.mk
index 39ff517..61269ce 100644
--- a/Android.mk
+++ b/Android.mk
@@ -19,7 +19,6 @@
 # Definitions applying to all targets. Be sure to $(eval) this last.
 define firewalld_common
   LOCAL_CPP_EXTENSION := .cc
-  LOCAL_RTTI_FLAG := -frtti
   LOCAL_CLANG := true
   LOCAL_SHARED_LIBRARIES += \
       libbrillo \