glsl: Add ir_unop_sin_reduced and ir_unop_cos_reduced

The operate just like ir_unop_sin and ir_unop_cos except that they
expect their inputs to be limited to the range [-pi, pi].  Several
GPUs require this limited range for their sine and cosine
instructions, so having these as operations (along with a to-be-written
lowering pass) helps this architectures.

These new operations also matche the semantics of the
GL_ARB_fragment_program SCS instruction.  Having these as operations
helps in generating GLSL IR directly from assembly fragment programs.

src/glsl/ir_constant_expression.cpp

@@ -216,6 +216,7 @@ ir_expression::constant_expression_value()
       break;
 
    case ir_unop_sin:
+   case ir_unop_sin_reduced:
       assert(op[0]->type->base_type == GLSL_TYPE_FLOAT);
       for (unsigned c = 0; c < op[0]->type->components(); c++) {
 	 data.f[c] = sinf(op[0]->value.f[c]);
@@ -223,6 +224,7 @@ ir_expression::constant_expression_value()
       break;
 
    case ir_unop_cos:
+   case ir_unop_cos_reduced:
       assert(op[0]->type->base_type == GLSL_TYPE_FLOAT);
       for (unsigned c = 0; c < op[0]->type->components(); c++) {
 	 data.f[c] = cosf(op[0]->value.f[c]);