implement -no-user-config command-line option (v3)

Changes v2 -> v3:
 - Rebase against latest qemu.git

Changes v1 -> v2:
 - Change 'userconfig' field/variables to bool instead of int
 - Coding style change

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/vl.c b/vl.c
index 4667bd2..91b18bc 100644
--- a/vl.c
+++ b/vl.c
@@ -2284,6 +2284,7 @@
     int show_vnc_port = 0;
 #endif
     bool defconfig = true;
+    bool userconfig = true;
     const char *log_mask = NULL;
     const char *log_file = NULL;
     GMemVTable mem_trace = {
@@ -2352,13 +2353,16 @@
             case QEMU_OPTION_nodefconfig:
                 defconfig = false;
                 break;
+            case QEMU_OPTION_nouserconfig:
+                userconfig = false;
+                break;
             }
         }
     }
 
     if (defconfig) {
         int ret;
-        ret = qemu_read_default_config_files();
+        ret = qemu_read_default_config_files(userconfig);
         if (ret < 0) {
             exit(1);
         }