autoconf 2.68b loops on Solaris 10 sparc (test 75)

[Paul Eggert]

The symptoms are:

$ cd tests; make check TESTSUITEFLAGS=75
make  check-local
/bin/bash ./testsuite 75
## ------------------------------ ##
## GNU Autoconf 2.68b test suite. ##
## ------------------------------ ##
 75: Configure re-execs self with CONFIG_SHELL

and it hangs until I do a ^C.

"truss" says /usr/bin/sh and ./cfg-sh are
execing each other.

My path is:

/var/run/rpc_door/eggert/prefix/bin:/usr/bin:/usr/sbin:/usr/perl5/bin:/usr/ccs/bin:/usr/dt/bin:/usr/openwin/bin:/usr/X11/bin:/opt/SUNWspro/bin:/usr/proc/bin:/sbin

That funny path in /var/run is where I've put GNU m4 1.4.16;
it doesn't contain anything else.