patch 9.1.0412: typo in regexp_bt.c in DEBUG code

Problem:  typo in regexp_bt.c in DEBUG code, causing
          compile error (@kfleong7, after v9.1.0409)
Solution: Replace bulen by buflen

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/regexp_bt.c b/src/regexp_bt.c
index 9da345f..5452dda 100644
--- a/src/regexp_bt.c
+++ b/src/regexp_bt.c
@@ -5570,7 +5570,7 @@
       case ZREF + 7:
       case ZREF + 8:
       case ZREF + 9:
-	bulen += sprintf(buf + buflen, "ZREF%d", OP(op) - ZREF);
+	buflen += sprintf(buf + buflen, "ZREF%d", OP(op) - ZREF);
 	p = NULL;
 	break;
 #endif
diff --git a/src/version.c b/src/version.c
index f4c792d..834954a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    412,
+/**/
     411,
 /**/
     410,