even if there were many divide by zero bugs.

The fix basically inlines all function calls to klee_div_zero_check()
so that each call to klee_report_error() is a unique instruction
for each instrumentation of a divide operation.

It also seems that inlining the call "magically" fixed the debug information
(file and line number) of the instruction so that the debug information on the
inlined instructions matches that of the instrumented division instruction.

Note that the command line option -emit-all-errors could be used to
workaround the bug fixed in this commit.