[compiler] miscellaneous trivial compiler warning fixes

[compiler] miscellaneous trivial compiler warning fixes

2006-01-19 Paul Jakma <paul.jakma@sun.com>

        * (general) various miscellaneous compiler warning fixes.
          Remove redundant break statements from switch clauses
          which return.
          return from main, not exit, cause it annoys SOS.
          Remove stray semi-colons which cause empty-statement
          warnings.
	* zebra/main.c: (sighup) remove private declaration of external
	  function.