[MINOR] add options dontlog-normal and log-separate-errors

Some big traffic sites have trouble dealing with logs and tend to
disable them. Here are two new options to help cope with massive
logs.

  - dontlog-normal only disables logging for 100% successful
    connections, other ones will still be logged

  - log-separate-errors will cause non-100% successful connections
    to be logged at level "err" instead of level "info" so that a
    properly configured syslog daemon can send them to a different
    file for longer conservation.
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 924019c..48d0a82 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -115,6 +115,8 @@
 #define PR_O2_SPLIC_ANY	(PR_O2_SPLIC_REQ|PR_O2_SPLIC_RTR|PR_O2_SPLIC_AUT)
 #define PR_O2_REQBUG_OK	0x00000008      /* let buggy requests pass through */
 #define PR_O2_RSPBUG_OK	0x00000010      /* let buggy responses pass through */
+#define PR_O2_NOLOGNORM	0x00000020      /* don't log normal traffic, only errors and retries */
+#define PR_O2_LOGERRORS	0x00000040      /* log errors and retries at level LOG_ERR */
 
 /* This structure is used to apply fast weighted round robin on a server group */
 struct fwrr_group {