Bug Fix: make sure /share gets mounted on boss.

We were missing a definition in installvars.pm. Also, uniformly treat
/share as optional in the install.

install/installvars.pm.in

@@ -341,6 +341,7 @@ $IMAGEPASSWORDSITEVAR   = "images/root_password";
 $MAILMANDIR		= "/usr/local/mailman";
 $MAILMANCFG		= "$MAILMANDIR/Mailman/mm_cfg.py";
 
+$SHAREDIR		= "@FSDIR_SHARE@";
 $SCRATCHDIR		= "@FSDIR_SCRATCH@";
 
 $OUTERBOSS_XMLRPCPORT   = "@OUTERBOSS_XMLRPCPORT@";

install/phases/dirs

@@ -17,9 +17,11 @@ sub Install($$$)
     if ($server eq $OPS_SERVERNAME || $server eq $FS_SERVERNAME) {
 	push(@TESTBED_DIRS, ([$USERROOT, "0755"],
 			     [$PROJROOT, "0755"],
-			     [$GROUPROOT, "0755"],
-			     [$SHAREROOT, "0775"]));
+			     [$GROUPROOT, "0755"]));
 
+	if ($SHAREDIR) {
+	    push(@TESTBED_DIRS, [$SHAREROOT, "0755"]);
+	}
 	if ($SCRATCHDIR) {
 	    push(@TESTBED_DIRS, [$SCRATCHROOT, "0755"]);
 	}

install/phases/exports

@@ -77,11 +77,11 @@ sub Install($$$)
 		}
 	    }
 
-	    if (ISFS($server)) {
-		#
-		# /share is special. We want to export to boss read-write,
-		# but to the control network read-only.
-		#
+	    #
+	    # /share is special. We want to export to boss read-write,
+	    # but to the control network read-only.
+	    #
+	    if ($SHAREDIR && ISFS($server)) {
 		my $realdir = `realpath $SHAREROOT`;
 		chomp($realdir);
 		push(@exports_lines,