vp: add test for pointsize output

progs/vp/psiz-mul.txt

+!!ARBvp1.0
+MOV result.color, vertex.color; 
+MUL result.pointsize, vertex.color.x, {10.0}.x; 
+MOV  result.position, vertex.position;
+END
+

progs/vp/vp-tris.c

 static GLuint nr_steps = 4;
 static GLuint prim = GL_TRIANGLES;
 static GLfloat psz = 1.0;
+static GLboolean pointsmooth = 0;
+static GLboolean program_point_size = 0;
 
 static void usage( char *name )
 {
    }
 }
 
+static void enable( GLenum value, GLboolean flag )
+{
+   if (flag)
+      glEnable(value);
+   else
+      glDisable(value);
+}
+
 /** Assignment */
 #define ASSIGN_3V( V, V0, V1, V2 )  \
 do {                                \
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glPointSize(psz);
 
+   enable( GL_POINT_SMOOTH, pointsmooth );
+   enable( GL_VERTEX_PROGRAM_POINT_SIZE_ARB, program_point_size );
+
    glBegin(prim);
 
 
       if (psz > .5)
          psz -= .5;
       break;
+   case 'm':
+      pointsmooth = !pointsmooth;
+      break;
+   case 'z':
+      program_point_size = !program_point_size;
+      break;
    case '+':
       nr_steps++;
       break;