Constify VEX's external interface.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2555 8f6e269a-dfd6-0310-a8e1-e2731360e62c
diff --git a/priv/main_main.c b/priv/main_main.c
index 8d81258..cf66cf1 100644
--- a/priv/main_main.c
+++ b/priv/main_main.c
@@ -203,7 +203,7 @@
    Int          (*emit)         ( /*MB_MOD*/Bool*,
                                   UChar*, Int, HInstr*, Bool,
                                   void*, void*, void*, void* );
-   IRExpr*      (*specHelper)   ( HChar*, IRExpr**, IRStmt**, Int );
+   IRExpr*      (*specHelper)   ( const HChar*, IRExpr**, IRStmt**, Int );
    Bool         (*preciseMemExnsFn) ( Int, Int );
 
    DisOneInstrFn disInstrFn;
@@ -1005,7 +1005,7 @@
 
 /* --------- Emulation warnings. --------- */
 
-HChar* LibVEX_EmNote_string ( VexEmNote ew )
+const HChar* LibVEX_EmNote_string ( VexEmNote ew )
 {
    switch (ew) {
      case EmNote_NONE: