patch 8.1.0855: cannot build xxd with MSVC 10

Problem:    Cannot build xxd with MSVC 10.
Solution:   Move declaration to start of block.
diff --git a/src/xxd/xxd.c b/src/xxd/xxd.c
index b8761fc..c24089e 100644
--- a/src/xxd/xxd.c
+++ b/src/xxd/xxd.c
@@ -472,6 +472,7 @@
   unsigned long displayoff = 0;
   static char l[LLEN+1];  /* static because it may be too big for stack */
   char *pp;
+  int addrlen = 9;
 
 #ifdef AMIGA
   /* This program doesn't work when started from the Workbench */
@@ -820,7 +821,6 @@
   else	/* hextype == HEX_BITS */
     grplen = 8 * octspergrp + 1;
 
-  int addrlen = 9;
   e = 0;
   while ((length < 0 || n < length) && (e = getc(fp)) != EOF)
     {