glsl: add several EmitNo* options, and MaxUnrollIterations

This increases the chance that GLSL programs will actually work.

Note that continues and returns are not yet lowered, so linking
will just fail if not supported.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
diff --git a/src/glsl/main.cpp b/src/glsl/main.cpp
index 2a7a713..94c14a5 100644
--- a/src/glsl/main.cpp
+++ b/src/glsl/main.cpp
@@ -215,7 +215,7 @@
 
 	 loop_state *ls = analyze_loop_variables(shader->ir);
 	 progress = set_loop_controls(shader->ir, ls) || progress;
-	 progress = unroll_loops(shader->ir, ls) || progress;
+	 progress = unroll_loops(shader->ir, ls, 32) || progress;
 	 delete ls;
       } while (progress);