Have framework include the common source files directly when building,
then build common as a static library separately (depending on
framework, like everything else).
Goes with a companion change to build/core/pathmap.mk.
but can also be used by unbundled apps. Move android.text.util.Regex there as
a starting example, renamed to a more sensible (?) com.android.common.Patterns.
Set up a corresponding test package, and move RegexTest (to PatternsTest).
Update clients.
