Integrate perlio:

[ 10586]
Add new step to run_byacc which:
A. Corrects #line NNN "perly.c" lines so warnings etc. are trackable
B. Adds extra () to the two if (var = ...) constructs gcc -Wall winges about.

[ 10584]
Hack to remove insecure directories from PATH so test will run.

p4raw-link: @10586 on //depot/perlio: f4db54055cd36d83622f77949fd6ab7c67198101
p4raw-link: @10584 on //depot/perlio: 24e8cdb889e0ad40169b18813ffa9d1841ab8217

p4raw-id: //depot/perl@10588