Ignore cc.Module.HideFromMake when producing flattened apex Android.mk entries

The modules in a flattened apex have suffixes that ensure they don't
conflict with the platform versions, so they can ignore HideFromMake.
This ensures that Make can install symbols for all libraries in
apexes.

Fixes: 180622230
Test: banchan com.android.adbd && m && ls $OUT/symbols/apex/com.android.adbd/lib
Change-Id: I76d1aba2eed6ae27d9a954bf88f40f0d00fc6a98