updated for version 7.3.446

Problem:    Win32: External commands with special characters don't work.
Solution:   Add the 'shellxescape' option.

src/option.c

@@ -2271,6 +2271,15 @@ static struct vimoption
 			    (char_u *)"\"",
 #else
 			    (char_u *)"",
+#endif
+				(char_u *)0L} SCRIPTID_INIT},
+    {"shellxescape", "sxe", P_STRING|P_VI_DEF|P_SECURE,
+			    (char_u *)&p_sxe, PV_NONE,
+			    {
+#if defined(MSDOS) || defined(WIN16) || defined(WIN3264)
+			    (char_u *)"\"&|<>()@^",
+#else
+			    (char_u *)"",
 #endif
 				(char_u *)0L} SCRIPTID_INIT},
     {"shiftround",  "sr",   P_BOOL|P_VI_DEF|P_VIM,