Extend ALLOW_MISSING_DEPENDENCIES coverage

Make build system respect ALLOW_MISSING_DEPENDENCIES, when building
architecture B products, and ignore targets with dependencies that
are not available for architecture B.

Bug: 142701187
Test: # Add a dummy Android.bp with a module only for arm64
      $ m -j TARGET_PRODUCT=aosp_x86 TARGET_BUILD_VARIANT=userdebug

Change-Id: I64de33674732df8c286671c806a07bcd19862b80