use calloc instead of malloc so try_codegen field is initialized to zero (bug 5791)
diff --git a/src/mesa/tnl/t_vb_arbprogram.c b/src/mesa/tnl/t_vb_arbprogram.c
index 0b76bd0..2599613 100644
--- a/src/mesa/tnl/t_vb_arbprogram.c
+++ b/src/mesa/tnl/t_vb_arbprogram.c
@@ -1,8 +1,8 @@
 /*
  * Mesa 3-D graphics library
- * Version:  6.4.1
+ * Version:  6.4.2
  *
- * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
+ * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -1395,7 +1395,7 @@
    const GLuint size = VB->Size;
    GLuint i;
 
-   stage->privatePtr = _mesa_malloc(sizeof(*m));
+   stage->privatePtr = _mesa_calloc(sizeof(*m));
    m = ARB_VP_MACHINE(stage);
    if (!m)
       return GL_FALSE;
@@ -1417,7 +1417,7 @@
    ASSIGN_4V(m->File[0][REG_LIT2], 1, .5, .2, 1); /* debug value */
 
    if (_mesa_getenv("MESA_EXPERIMENTAL"))
-      m->try_codegen = 1;
+      m->try_codegen = GL_TRUE;
 
    /* Allocate arrays of vertex output values */
    for (i = 0; i < VERT_RESULT_MAX; i++) {