Start using best resilience expansion in SIL

[slavapestov]

Follow-up to #23263.

Peeling patches from #23170 to identify the code size regression. These are the first two patches in the series that actually change behavior; they should have minimal impact either way though.

rdar://problem/24057844, https://bugs.swift.org/browse/SR-261.

[slavapestov]

@swift-ci Please benchmark

[slavapestov]

@swift-ci Please smoke test

[slavapestov]

@swift-ci Please test source compatibility

[swift-ci]

Performance: -Osize

TEST	OLD	NEW	DELTA	RATIO
Improvement
StringBuilderWithLongSubstring	1540	1430	-7.1%	1.08x (?)

How to read the data

The tables contain differences in performance which are larger than 8% and differences in code size which are larger than 1%.

If you see any unexpected regressions, you should consider fixing the
regressions before you merge the PR.

Noise: Sometimes the performance results (not code size!) contain false
alarms. Unexpected regressions which are marked with '(?)' are probably noise.
If you see regressions which you cannot explain you can try to run the
benchmarks again. If regressions still show up, please consult with the
performance team (@eeckstein).

Hardware Overview

  Model Name: Mac Pro
  Model Identifier: MacPro6,1
  Processor Name: 12-Core Intel Xeon E5
  Processor Speed: 2.7 GHz
  Number of Processors: 1
  Total Number of Cores: 12
  L2 Cache (per Core): 256 KB
  L3 Cache: 30 MB
  Memory: 64 GB

[slavapestov]

@swift-ci Please smoke test Linux