* Adds RangeSet/DiscontiguousSlice to the stdlib
* Remove redundant DiscontiguousSlice.Index: Comparable conformance
* Attempt to fix embedded build
* Attempt to fix macOS test failures
* Fix Constaints/members.swift failure on linux
* Add exceptions to ABI/source checker to fix macOS tests
* Fix incremental dependency test failure
* Remove inlining/unfreeze implementation for future improvements
* Simplify indices(where:) implementation
* Address review feedback
* Add test for underscored, public slice members
* Address feedback on inlining, hashing, and initializing with unordered arrays
* Fix ABI checker issues
* Remove MutableCollection extension for DiscontiguousSlice
* Make insertion return a discardable Bool
* Fix ABI checker tests
* Fix other ABI checker tests due to dropping MutableCollection subscript
The framework baselines are installed at 'lib/swift/FrameworkABIBaseline' and the
tool is inside 'bin'. This patch teaches the executable to locate baselines
from the relative path.
In addition, this patch moves the stdlib ABI/API baselines to the canonical
location so we don't have to check the stability of the stdlib using a
different mechanism from other Swift frameworks.
