Added ctx->Vertex/FragmentProgram._Enable flags.  Set when vertex/fragment
program is enabled AND the currently bound program is valid.
Check _Enable instead of Enable to prevent things from blowing up
when someone calls glEnable(GL_VERTEX_PROGRAM_ARB) without actually
defining a program.
diff --git a/src/mesa/shader/program.c b/src/mesa/shader/program.c
index 6c1e362..63fc865 100644
--- a/src/mesa/shader/program.c
+++ b/src/mesa/shader/program.c
@@ -1,6 +1,6 @@
 /*
  * Mesa 3-D graphics library
- * Version:  6.0
+ * Version:  6.1
  *
  * Copyright (C) 1999-2004  Brian Paul   All Rights Reserved.
  *
@@ -1142,7 +1142,7 @@
                         "glGetProgramRegisterfvMESA(target)");
             return;
          }
-         if (!ctx->VertexProgram.Enabled) {
+         if (!ctx->VertexProgram._Enabled) {
             _mesa_error(ctx, GL_INVALID_OPERATION,
                         "glGetProgramRegisterfvMESA");
             return;
@@ -1194,7 +1194,7 @@
                         "glGetProgramRegisterfvMESA(target)");
             return;
          }
-         if (!ctx->FragmentProgram.Enabled) {
+         if (!ctx->FragmentProgram._Enabled) {
             _mesa_error(ctx, GL_INVALID_OPERATION,
                         "glGetProgramRegisterfvMESA");
             return;
@@ -1207,7 +1207,7 @@
                         "glGetProgramRegisterfvMESA(target)");
             return;
          }
-         if (!ctx->FragmentProgram.Enabled) {
+         if (!ctx->FragmentProgram._Enabled) {
             _mesa_error(ctx, GL_INVALID_OPERATION,
                         "glGetProgramRegisterfvMESA");
             return;