Also modify a log message for better clarity

Previous logic would result in error if Slurm version > 17.11

The problem was the tests set the same variable, opt_arg, for for
options, --test_suite and --test_suite_reg. But with the addition of
de24ce72 the variable was being set with the different numbers out
of order because the variable was being set from the environment. So the
fix is to have the options set their own variable.

Bug 4176

to avoid name collisions with c++ list types. gdb started showing the
wrong type when the full lib was created.

to set -O0 since --enable-developer and --enable-debug set
optimizations.

What appears to have happened is we changed only the non-internal setup.  So
technically this isn't needed, but does help with handling confusion later.

Coverity CID 44977

_alloc_mask() can return NULL, which was not handled.
Coverity CID 44859

Kept separate for clarity.

Bug 4014.

Note: This check is needed since the maximum file path length really
  is file system dependent and not something local to the Linux distro
Coverity CID 45200

Coverity CID 45343

Really should not happen, but this adds checks
Coverity CID 171449

Coverity CID 45167

Coverity CID 44823

Coverity CID 45160