GLSL fixes:

- generate error on NULL pointers in glShaderSourceARB;
- reinstall program object, if current, in glLinkProgramARB;
- vertex and fragment shaders are optional in program object;
- floor asm was wrongly computed for x86 back-end;
- allow for (void) idiom in function prototypes;
- all fixed-state uniforms are updated;
- local variable initializers are working;
- implement texture* and shadow* functions for vertex processor;
- generate error if too many arguments in general constructor;
- trim unused data in general constructor;
- struct r-value field select was badly relocated;

Changes:
- add derived state gl_fog_attrib::_Scale;
- add derived state gl_light::_CosCutoffNeg;

src/mesa/tnl/t_vb_arbprogram.c

@@ -1264,7 +1264,7 @@ run_arb_vertex_program(GLcontext *ctx, struct tnl_pipeline_stage *stage)
    GLuint i, j;
    GLbitfield outputs;
 
-   if (ctx->ShaderObjects.CurrentProgram != NULL)
+   if (ctx->ShaderObjects._VertexShaderPresent)
       return GL_TRUE;
 
    program = (ctx->VertexProgram._Enabled ? ctx->VertexProgram.Current : ctx->_TnlProgram);
@@ -1427,7 +1427,7 @@ validate_vertex_program( GLcontext *ctx, struct tnl_pipeline_stage *stage )
    struct arb_vp_machine *m = ARB_VP_MACHINE(stage);
    struct vertex_program *program;
 
-   if (ctx->ShaderObjects.CurrentProgram != NULL)
+   if (ctx->ShaderObjects._VertexShaderPresent)
       return;
 
    program = (ctx->VertexProgram._Enabled ? ctx->VertexProgram.Current : 0);