In ipcclean, check LOGNAME only if USER is not set.

Fixes problem with 'su' on some platforms.

src/bin/ipcclean/ipcclean.sh

 #!/bin/sh
 #
-# $PostgreSQL: pgsql/src/bin/ipcclean/ipcclean.sh,v 1.16 2006/01/05 01:56:29 momjian Exp $
+# $PostgreSQL: pgsql/src/bin/ipcclean/ipcclean.sh,v 1.17 2006/03/03 16:49:21 momjian Exp $
 #
 
 CMDNAME=`basename $0`
@@ -19,7 +19,8 @@ if [ "$1" = '-?' -o "$1" = "--help" ]; then
     exit 0
 fi
 
-if [ "$USER" = 'root' -o "$LOGNAME" = 'root' ]
+# only check $LOGNAME if $USER is not set
+if [ "$USER" = 'root' -o \( ! "$USER" -a "$LOGNAME" = 'root' \) ]
 then
   (
     echo "$CMDNAME: cannot be run as root" 1>&2