Revert "Make function parameters and refutable patterns always
immutable"
This reverts commit 8f2fbdc93a.
Once we have finally merged master into the Swift 2.2 branch to be, we
should revert this commit to turn the errors back on for Swift 3.0.
All refutable patterns and function parameters marked with 'var'
is now an error.
- Using explicit 'let' keyword on function parameters causes a warning.
- Don't suggest making function parameters mutable
- Remove uses in the standard library
- Update tests
rdar://problem/23378003
The code goes into its own sub-tree under 'tools' but tests go under 'test',
so that running 'check-swift' will also run all the SourceKit tests.
SourceKit is disabled on non-darwin platforms.