swift234

Remove AssertDebug hack and fixup make files

When we build the standard libary with -parse-stdlib the frontend sets the
assert configuration to 'DisableReplacement'. Constant replacement does not take
place and the call to the builtin function 'assert_configuration' call stays in
the serialize SIL of the swiftmodule.

IRGen replaces the function call to the assert_configuration builtin function by
the value for Debug (0). The resuling standard library dylib hence contains the
debug version of the standard library assert function.

Frontend optimization flags can now determine whether asserts should be executed
or not.

This commit removes the SWIFT_ASSERTS cmake flag.

rdar://16458612

Swift SVN r16473