This improves forexecbench performance on josmp by about 18%.  Now
steal_nonexec = 0 seems to have no affect or maybe a small negative
affect.

add "EXCEPTIONS := n" to config.mk

handle out-of-memory situations without requiring memory allocation.

(links, but crashes if an exception is thrown).

explicitly add gcc's own headers for stdarg.h

The critical wq allows pushing to remote cores and cores never
steal from the critical wq.