setup critical edge breaking to 1) emit a map of critical edges, and 2) parameterize which edge types get broken

reworked the red-zone detector to do better than just using leaf functions, as we found the red zone used in a non-leaf function

updating zafl.sh and zax to using command line args instead of env for communicating fixed-map addressing

When name of function is specified as entry point for fork server,
pre-insert the fork server init code at the last instruction of the
first basic block in the function.

One version returns a value. STARS is able to find a dead reg.
2nd func if void. STARS finds no dead regs.

The dominator graph algorith completely makes this optimization obsolete.