maint: avoid C99 loop declaration

Commit 3d0e3c1a reintroduced a problem previously squelched in
commit 7e5aa78d.  Add a syntax check this time around.

util/virutil.c: In function 'virGetGroupList':
util/virutil.c:1015: error: 'for' loop initial declaration used outside C99 mode

* cfg.mk (sc_prohibit_loop_var_decl): New rule.
* src/util/virutil.c (virGetGroupList): Fix offender.
Signed-off-by: NEric Blake <eblake@redhat.com>

cfg.mk

@@ -555,6 +555,12 @@ sc_prohibit_loop_iijjkk:
 	halt='use i, j, k for loop iterators, not ii, jj, kk' 		\
 	  $(_sc_search_regexp)
 
+# RHEL 5 gcc can't grok "for (int i..."
+sc_prohibit_loop_var_decl:
+	@prohibit='\<for *\(\w+[ *]+\w+'				\
+	in_vc_files='\.[ch]$$'						\
+	halt='declare loop iterators outside the for statement'		\
+	  $(_sc_search_regexp)
 
 # Many of the function names below came from this filter:
 # git grep -B2 '\<_('|grep -E '\.c- *[[:alpha:]_][[:alnum:]_]* ?\(.*[,;]$' \

src/util/virutil.c

@@ -1010,18 +1010,18 @@ virGetGroupList(uid_t uid, gid_t gid, gid_t **list)
     }
 
     if (gid != (gid_t)-1) {
-        size_t n = ret;
+        size_t i;
 
-        for (size_t i = 0; i < ret; i++) {
+        for (i = 0; i < ret; i++) {
             if ((*list)[i] == gid)
                 goto cleanup;
         }
-        if (VIR_APPEND_ELEMENT(*list, n, gid) < 0) {
+        if (VIR_APPEND_ELEMENT(*list, i, gid) < 0) {
             ret = -1;
             VIR_FREE(*list);
             goto cleanup;
         } else {
-            ret = n;
+            ret = i;
         }
     }