Make bitmap compression retain the ColorSpace

Bug: 147877556
Test: I72b5f28903a67445bc205cdad8848384ad675b31

In Bitmap#compress and AndroidBitmap_compress, remove the conversion
from F16 to 8888 P3. This was originally done because F16 forced a
particular ColorSpace, and we wanted to use a wider gamut than SRGB.
Now that F16 can be any RGB ColorSpace, encode it with the ColorSpace
that it already has. Skip the conversion to 8888, which is unnecessary.
The encoders can already convert from F16.

Remove Bitmap::CompressResult. Now that compress does not allocate a
Bitmap, there is no reason to return ALLOCATION_FAILED.

Change-Id: I8190664398e762daf57092d919f382a56267dd07