Most of the tests just got moved to swiftc, but some of them were
duplicated to apply to both swiftc and swift. A handful still use the
existing 'swift' because they are for the existing '-i' syntax.
Note: this means config.swift_driver now uses the staging symlink
'swifti'. The only thing preventing us from dropping the 'i' and getting
rid of the old interface is that Xcode hasn't moved to swiftc yet
<rdar://problem/17769327>.
Swift SVN r20467
Rather than embed AST info directly in binaries, we now include a special
symbol table entry that points to the serialized AST as a separate file.
This requires a very recent version of ld.
We still want to support the __SWIFT,__ast section in a binary because
that's how it's modeled in dSYM, so manually test both modes in
ASTSection_linker.swift.
Part of <rdar://problem/15796201>.
Swift SVN r20421