review request (XS) - 6718879 & 6769128

[John Coomes]

http://webrev.invokedynamic.info/jcoomes/6718879-build/

Details are in the bug reports.  It may take a while for the updates
to 6769128 propogate to bugs.sun.com, so

6718879: cannot build on solaris nevada

	Remove the assignment to ia_nice from os_solaris.cpp.

6769128: failure to run generateJvmOffsets is ignored

	Use a separate shell command to run generateJvmOffsets in
	dtrace.make.  I also created a make macro to avoid repeating
	the shell command that conditionally updates the generated
	JvmOffset* files.

Two files, 24 lines total.

-John