Fix ARB_fp spec conformance bug WRT shadow sampling.

The ARB_fp (and other assembly-level fragment program specs) say that the
depth comparison function is always GL_NONE in fragment program mode.

src/mesa/swrast/s_fragprog.c

@@ -26,6 +26,7 @@
 #include "colormac.h"
 #include "context.h"
 #include "prog_instruction.h"
+#include "texstate.h"
 
 #include "s_fragprog.h"
 #include "s_span.h"
@@ -199,6 +200,7 @@ void
 _swrast_exec_fragment_program( GLcontext *ctx, SWspan *span )
 {
    const struct gl_fragment_program *program = ctx->FragmentProgram._Current;
+   GLuint i;
 
    /* incoming colors should be floats */
    if (program->Base.InputsRead & FRAG_BIT_COL0) {
@@ -207,8 +209,22 @@ _swrast_exec_fragment_program( GLcontext *ctx, SWspan *span )
 
    ctx->_CurrentProgram = GL_FRAGMENT_PROGRAM_ARB; /* or NV, doesn't matter */
 
+   for (i = 0; i < ctx->Const.MaxTextureImageUnits; i++) {
+      if (ctx->Texture.Unit[i]._Current != NULL) {
+         _mesa_update_texture_compare_function(ctx->Texture.Unit[i]._Current,
+                                               GL_TRUE);
+      }
+   }
+
    run_program(ctx, span, 0, span->end);
 
+   for (i = 0; i < ctx->Const.MaxTextureImageUnits; i++) {
+      if (ctx->Texture.Unit[i]._Current != NULL) {
+         _mesa_update_texture_compare_function(ctx->Texture.Unit[i]._Current,
+                                               GL_FALSE);
+      }
+   }
+
    if (program->Base.OutputsWritten & (1 << FRAG_RESULT_COLR)) {
       span->interpMask &= ~SPAN_RGBA;
       span->arrayMask |= SPAN_RGBA;