patch 7.4.1399

Problem:    The MS-DOS code does not build.
Solution:   Remove the old MS-DOS code.

src/regexp.c

@@ -1338,12 +1338,6 @@ bt_regcomp(char_u *expr, int re_flags)
     if (reg(REG_NOPAREN, &flags) == NULL)
 	return NULL;
 
-    /* Small enough for pointer-storage convention? */
-#ifdef SMALL_MALLOC		/* 16 bit storage allocation */
-    if (regsize >= 65536L - 256L)
-	EMSG_RET_NULL(_("E339: Pattern too long"));
-#endif
-
     /* Allocate space. */
     r = (bt_regprog_T *)lalloc(sizeof(bt_regprog_T) + regsize, TRUE);
     if (r == NULL)