It is not visually noticeable but apparently affected by kern format2 correct implementation.
I should've checked CoreText result which can't as CircleCI outage.

Fixes https://github.com/harfbuzz/harfbuzz/issues/1421

Optimize harfbuzz big integer conversions

Profiling showed that type conversions were adding considerable cycles in time
spent doing text shaping.

The idea is to optimize it using native processor instructions to help Blink
layout performance.

Doing further investigation revelead that compilers may not use the
proper instruction on ARM 32bits builds (i.e. REV16).

One way to insure that the generated ASM was ideal for both gcc/clang
was using __builtin_bswap16.

Added bonus is that we no longer need to test for CPU architecture.

Similar to https://github.com/GoogleChrome/lighthouse/blob/master/.codecov.yml

No strong preference on commenting, feel free to enable it again

Fixes https://github.com/harfbuzz/harfbuzz/issues/1410

Fixes https://github.com/harfbuzz/harfbuzz/pull/1346

They are not sorted.

Since it was pages and pages...