Make external decls of tasking layer functions match their defs.

The ChapelLocale module's external declarations of 4 functions in the
tasking layer interface didn't match the definitions of those same
functions.  Fix the decls.
Merge pull request #139 from gbtitus/modules-taskrt-interface

Make external decls of tasking layer functions match their defs.

[Reviewed by Sung.]

The ChapelLocale module's external declarations of 4 functions in the
tasking layer interface didn't match the definitions of those same
functions. Fix the decls.