Configure nits: do not use /tmp to avoid potential security

Configure nits: do not use /tmp to avoid potential security
problems (Andy Dougherty: this does not fix the rampant
use of /tmp by the various utilities like C compilers, though.
Just don't run Configure as root if you care about security.),
fix man3dir bug (both from Andy Dougherty); fix hints files
not to use /tmp; retract #4993 (the description of the *symbols
variables is okay, after all); regen Configure.

p4raw-id: //depot/cfgperl@5757