Fix for PR libc/1686

[Andreas Jaeger]

Thanks Mark.

Shouldn't we change the other places also?

$ grep -r /bin/pwd . 
./ChangeLog:    * Makerules: Use $(PWD_P) instead of /bin/pwd.
./ChangeLog.7:  pwd as /bin/pwd and /usr/bin/pwd.
./ChangeLog.7:  * rellnsh-sh: Use explicitely /bin/pwd to find the external program.
./scripts/rellns-sh:if test -x /bin/pwd; then
./scripts/rellns-sh:  pwd=/bin/pwd
./scripts/rellns-sh:elif test -x /usr/bin/pwd; then
./scripts/rellns-sh:  pwd=/usr/bin/pwd
./io/ftwtest-sh:tmpreal=`cd $tmp; /bin/pwd 2>/dev/null || /usr/bin/pwd`

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de