Bug 622903 - fix coverity Defect Type: Code maintainability issues

https://bugzilla.redhat.com/show_bug.cgi?id=622903

Comment:
The str assignment on line 1240 can be removed because the value
is not needed or will be overwritten.

ldap/servers/plugins/acl/aclutil.c

@@ -1237,7 +1237,7 @@ acl_replace_str(char * s, char *substr, char* replace_with_str) {
 		char *working_s, *suffix, *prefix, *patched;
 		int replace_with_len, substr_len, prefix_len, suffix_len;
 
-		if ( (str = strstr(s, substr)) == NULL) {
+		if (strstr(s, substr) == NULL) {
 			return(slapi_ch_strdup(s));
 		} else {