Compute SparseBitSet for cmap format 14 subtables.

By computing cmap format 14 subtables similar to cmap format 4 or 12,
there are following benefits:
- FontCollection::hasVariationSelector becomes 70x faster for the worst
  case, 10x faster for the normal case.
- FontFamily::hasGlyph becomes lock-free.
- FontCollection::itemize becomes 2x faster than before for some cases.

On the other hand, following negative things happen:
- Initial FontFamily construction takes 2.5x longer than before, but this
only happens in Zygote and should not happen at application launch time.
- FontFamily construction from buffer takes longer time than before but
it is still around 800µs.
- Consumes additionally memory (about 30kB for NotoSansCJK-Regular.ttc
of ttc index 0, 2.5kB for NotoColorEmoji.ttf), but this is shared across
all applications. No additional memory is necessary if the font doesn't
support variation sequences.

Bug: 36401726
Test: minikin_tests passed
Test: minikin_stress_tests passed
Test: android.graphics.cts.PaintTest passed
Merged-In: I3ebc9ad5050fb9ab6283810d31ae8d13af168ec5
Change-Id: Ia84c4b56aed35a899223e33c1a4a15734de58c33

• include/minikin/CmapCoverage.h[diff]
• include/minikin/FontFamily.h[diff]
• libs/minikin/CmapCoverage.cpp[diff]
• libs/minikin/FontCollection.cpp[diff]
• libs/minikin/FontFamily.cpp[diff]
• libs/minikin/MinikinInternal.cpp[diff]
• libs/minikin/MinikinInternal.h[diff]
• tests/stresstest/Android.mk[diff]
• tests/stresstest/FontFamilyTest.cpp[Added - diff]
• tests/unittest/CmapCoverageTest.cpp[diff]
• tests/unittest/FontFamilyTest.cpp[diff]