"autoreply" flag: autogenerate standard xxx_reply_t messages

Change-Id: I72298aaae7d172082ece3a8edea4217c11b28d79
Signed-off-by: Dave Barach <dave@barachs.net>
diff --git a/src/tools/vppapigen/gram.y b/src/tools/vppapigen/gram.y
index de26af8..9cea602 100644
--- a/src/tools/vppapigen/gram.y
+++ b/src/tools/vppapigen/gram.y
@@ -38,7 +38,7 @@
 %token NAME RPAR LPAR SEMI LBRACK RBRACK NUMBER PRIMTYPE BARF
 %token TPACKED DEFINE LCURLY RCURLY STRING UNION
 %token HELPER_STRING COMMA 
-%token NOVERSION MANUAL_PRINT MANUAL_ENDIAN TYPEONLY DONT_TRACE
+%token NOVERSION MANUAL_PRINT MANUAL_ENDIAN TYPEONLY DONT_TRACE AUTOREPLY
 
 %%
 
@@ -64,6 +64,7 @@
         | MANUAL_ENDIAN         {$$ = $1;}
         | DONT_TRACE            {$$ = $1;}
         | TYPEONLY              {$$ = $1;}
+        | AUTOREPLY             {$$ = $1;}
           ;
 
 defn:     DEFINE NAME LCURLY defbody RCURLY SEMI