Exposes the global warning suppression and treatment as errors
functionality to the Swift driver. Introduces the flags
"-suppress-warnings" and "-warnings-as-errors". Test case include.
Previously, the frontend detected that its output was being piped into the
driver and buffered, and decided that that wasn't a color-friendly output
stream. Now, the driver passes -color-diagnostics to the frontend to force
color output if the driver itself is in a color-output context.
<rdar://problem/16697713>
Swift SVN r18506
Added a new DiagnosticOptions class to swiftBasic, and added a DiagnosticOptions member to CompilerInvocation.
Added a static ParseDiagnosticArgs function to parse diagnostic-related arguments.
Added -verify to FrontendOptions.td, and added support for parsing -verify in ParseDiagnosticArgs.
Updated frontend_main() to enable and trigger the DiagnosticVerifier when -verify is passed.
Swift SVN r11318
