Set min_sdk_version to be part of mainline modules

Modules contributing mainline modules (APK/APEX) should set
min_sdk_version as well as apex_available.

- libstagefright_headers
- libstagefright_esds
- libstagefright_metadatautils
- libstagefright_mpeg2extractor
- libstagefright_m4vh263dec
- libstagefright_m4vh263enc

For now setting min_sdk_version doesn't change build outputs.
But build-time checks will be added soon.

Exempt-From-Owner-Approval: cherrypick from master

Bug: 152655956
Test: m
Merged-In: I821b309ac5b4cfc7d83da69f6715fc327824cb66
Change-Id: I821b309ac5b4cfc7d83da69f6715fc327824cb66
(cherry picked from commit 5e8fecc3)