paexec -x:
* fix handling tasks with leading spaces
* fix handling tasks with backslashes
paargs:
* on SunOS-5.10 use /usr/xpg4/bin/sh
instead of horribly broken /bin/sh
Fix build failure on SunOS-5.10 (getdelim(3) is absent)
Introduce PAEXEC_SH environment variable
for fixing /bin/sh on SunOS-5.10
Introduce PAEXEC_FIND variable for regression tests (required on
SunOS-5.10)