Force icu4c to always default to the Gregorian calendar.

This matches the Java side of the system (and pre-KitKat behavior).

Bug: 12004664

(cherry-picked from b844b3e14e24df5b8d9b25539f6eb92ac507d8b4)

Change-Id: I2462e9a8af288535a1511f7cb3bba9dd459a8ed3
Merge branch 'kitkat-mr2.2-release' of https://android.googlesource.com/platform/external/icu4c into kk4.4