REGTEST: Fix several issues.

Use #!bin/sh more portable shebang.
Support filenames with spaces.
Set HAPROXY_PROGRAM environment variable value to ${PWD}/haproxy.
exit(1) if we could not creat the higher level temporary working directory
or create its sub-directory with mktemp utility.
As defined by POSIX, use six characters for the mktemp template.
1 file changed