Deal with CPU models in []

Qemu committed a patch which list some CPU names in [] when asked for
supported CPUs (qemu -cpu ?). Yet, it needs such CPUs to be passed
without those square braces. When probing for supported CPU models, we
can just strip the square braces and pretend we have never seen them.

src/qemu/qemu_conf.c

@@ -628,7 +628,9 @@ typedef int
                        const char ***retcpus);
 
 /* Format:
- * <arch> <model>
+ *      <arch> <model>
+ * qemu-0.13 encloses some model names in []:
+ *      <arch> [<model>]
  */
 static int
 qemudParseX86Models(const char *output,
@@ -661,15 +663,22 @@ qemudParseX86Models(const char *output,
             continue;
 
         if (retcpus) {
+            unsigned int len;
+
             if (VIR_REALLOC_N(cpus, count + 1) < 0)
                 goto error;
 
             if (next)
-                cpus[count] = strndup(p, next - p - 1);
+                len = next - p - 1;
             else
-                cpus[count] = strdup(p);
+                len = strlen(p);
+
+            if (len > 2 && *p == '[' && p[len - 1] == ']') {
+                p++;
+                len -= 2;
+            }
 
-            if (!cpus[count])
+            if (!(cpus[count] = strndup(p, len)))
                 goto error;
         }
         count++;