swift234

[SIL Printer] Add optional source location printing.

Added a -v(verbose) option to swift that will trigger verbose printing in SIL
Printer. SIL Printer will print the location info only in the verbose mode.

Here is the example of the format - only the line and colon are displayed for
brevity:

%24 = apply %13(%22) : $[cc(method), thin] ((), [byref] Bool) -> Builtin.Int1 // user: %26 line:46:10

(This will be used to test the validity of SILLocation info.)

Swift SVN r6991