Add a 32-bit x86_64 arch variant

In make, the current 32-bit configuration for generic x86_64 targets
inherits some variables (SSE4 support) from the 64-bit configuration,
and overrides the make variables used for other configurations (SSSE3).

We don't have that problem in Soong, but this is the configuration
matching what Make is using.

Change-Id: Ia934ff40f9388f9c202a0fe0608e7b45b77a2714
2 files changed