Fix crash

See merge request allzp/zfuzz!8

Building CFGs seems to require that the assembly is correct
Force building of the assembly after making mods to the IR
and before building a new CFG

Resolve "Add context sensitivity to zafl instrumentation"

Closes #40

See merge request allzp/zfuzz!7

updated zafl.sh with better help screen, debugged zax-base to properly implement domgraph optimziation

filter entry block if has exactly 1 successor
filter exit blocks if have exactly 1 predecessor

Before eliding conditional branch,  verify that neither successor is IBTA