Libcore: Refactor TimeZone for compile-time initialization

Introduce a private inner class for custom-time-zone parsing. This
moves the Pattern field which cannot be compile-time initialized.

As a result, TimeZone, SimpleTimeZone & ZoneInfo can be initialized
in the boot image.

Bug: 19542228
Change-Id: I6fc8cb65975e14351a6bfc1ddfac175368efd1eb
1 file changed