Support extra linespacing based on fallback fonts

* Increase the ascent and descent of individual lines in StaticLayout
  as needed, if any fallback fonts that end up getting used call for
  it. For backward compatibility, this is hidden behind a builder
  flag.
* Document in Paint.java that the returned parameters are only for
  the default font, and a layout may need more space based on
  fallbacks used.

Also update for changes in minikin API:

* MinikinFont now requires a method for getting vertical extents
  (ascent, descent, and line gap).
* minikin API now allows asking for vertical extents of laid out
  text.
* minikin API's LineBreaker now returns ascents and descents for each
  line.

Finally, added performances test for creating a StaticLayout.
Follwing are the numbers on a marlin with a stable clock before and
after this CL.

For fixed text almost always hitting the cache:
Before: mean=260684 median=260188 min=258532 standardDeviation=1897
After:  mean=262432 median=261509 min=260429 standardDeviation=2185

For random text almost never hitting the cache:
Before: mean=5971827 median=5991126 min=5886871 standardDeviation=83724
After:  mean=6337093 median=6317010 min=6311222 standardDeviation=40213

Bug: 28963299
Bug: 29063863
Bug: 32057121
Bug: 37756858
Test: bit FrameworksCoreTests:android.text.
Test: bit CtsTextTestCases:*
Change-Id: I482a98ff8f472e8bab4f0ba9d1d7b368858038ff