gsdx-ogl: add extensions check that might be useful in the future

Namely
* GL_ARB_multi_bind
* GL_ARB_vertex_attrib_binding
* GL_ARB_shader_storage_buffer_object
* GL_ARB_sparse_texture
* GL_ARB_sparse_texture2
* GL_ARB_compute_shader
* GL_ARB_texture_view

v2: add default option value

plugins/GSdx/GSdx.cpp

@@ -396,15 +396,22 @@ void GSdxApp::Init()
	m_default_configuration["osd_monitor_enabled"]                        = "0";
	m_default_configuration["osd_max_log_messages"]                       = "2";
	m_default_configuration["override_geometry_shader"]                   = "-1";
	m_default_configuration["override_GL_ARB_compute_shader"]             = "-1";
	m_default_configuration["override_GL_ARB_copy_image"]                 = "-1";
	m_default_configuration["override_GL_ARB_clear_texture"]              = "-1";
	m_default_configuration["override_GL_ARB_clip_control"]               = "-1";
	m_default_configuration["override_GL_ARB_direct_state_access"]        = "-1";
	m_default_configuration["override_GL_ARB_draw_buffers_blend"]         = "-1";
	m_default_configuration["override_GL_ARB_get_texture_sub_image"]      = "-1";
	m_default_configuration["override_GL_ARB_gpu_shader5"]                = "-1";
	m_default_configuration["override_GL_ARB_multi_bind"]                 = "-1";
	m_default_configuration["override_GL_ARB_shader_image_load_store"]    = "-1";
	m_default_configuration["override_GL_ARB_shader_storage_buffer_object"] = "-1";
	m_default_configuration["override_GL_ARB_sparse_texture"]             = "-1";
	m_default_configuration["override_GL_ARB_sparse_texture2"]            = "-1";
	m_default_configuration["override_GL_ARB_viewport_array"]             = "-1";
	m_default_configuration["override_GL_ARB_texture_view"]               = "-1";
	m_default_configuration["override_GL_ARB_vertex_attrib_binding"]      = "-1";
	m_default_configuration["override_GL_ARB_texture_barrier"]            = "-1";
	m_default_configuration["override_GL_EXT_texture_filter_anisotropic"] = "-1";
	m_default_configuration["paltex"]                                     = "0";

plugins/GSdx/Renderers/OpenGL/GLLoader.cpp

@@ -145,7 +145,6 @@ namespace GLLoader {
	bool in_replayer        = false;
	bool buggy_sso_dual_src = false;


	bool found_geometry_shader = true; // we require GL3.3 so geometry must be supported by default
	bool found_GL_EXT_texture_filter_anisotropic = false;
	bool found_GL_ARB_clear_texture = false;
@@ -154,12 +153,19 @@ namespace GLLoader {
	bool found_GL_ARB_gpu_shader5 = false; // Require IvyBridge
	bool found_GL_ARB_shader_image_load_store = false; // Intel IB. Nvidia/AMD miss Mesa implementation.
	bool found_GL_ARB_viewport_array = false; // Intel IB. AMD/NVIDIA DX10
	bool found_GL_ARB_shader_storage_buffer_object = false;
	bool found_GL_ARB_sparse_texture = false;
	bool found_GL_ARB_sparse_texture2 = false;
	bool found_GL_ARB_compute_shader = false;
	bool found_GL_ARB_texture_view = false; // maybe older gpu can support it ?
	// Bonus to monitor the VRAM
	bool found_GL_NVX_gpu_memory_info = false;

	// Mandatory
	// Mandatory in the future
	bool found_GL_ARB_direct_state_access = false;
	bool found_GL_ARB_texture_barrier = false;
	bool found_GL_ARB_multi_bind = false;
	bool found_GL_ARB_vertex_attrib_binding = false;

	static bool mandatory(const std::string& ext)
	{
@@ -292,15 +298,22 @@ namespace GLLoader {
		{
			// Bonus
			status &= optional(found_GL_EXT_texture_filter_anisotropic, "GL_EXT_texture_filter_anisotropic"); // ARB extension in 4.6
			status &= optional(found_GL_ARB_sparse_texture, "GL_ARB_sparse_texture");
			status &= optional(found_GL_ARB_sparse_texture2, "GL_ARB_sparse_texture2");
			// GL4.0
			status &= optional(found_GL_ARB_gpu_shader5, "GL_ARB_gpu_shader5");
			// GL4.1
			status &= optional(found_GL_ARB_viewport_array, "GL_ARB_viewport_array");
			// GL4.2
			status &= optional(found_GL_ARB_shader_image_load_store, "GL_ARB_shader_image_load_store");
			// GL4.3
			status &= optional(found_GL_ARB_compute_shader, "GL_ARB_compute_shader");
			status &= optional(found_GL_ARB_shader_storage_buffer_object, "GL_ARB_shader_storage_buffer_object");
			status &= optional(found_GL_ARB_texture_view, "GL_ARB_texture_view");
			status &= optional(found_GL_ARB_vertex_attrib_binding, "GL_ARB_vertex_attrib_binding");
			// GL4.4
			status &= optional(found_GL_ARB_clear_texture,"GL_ARB_clear_texture");
			status &= optional(found_GL_ARB_multi_bind,"GL_ARB_multi_bind");
			// GL4.5
			status &= optional(found_GL_ARB_direct_state_access, "GL_ARB_direct_state_access");
			// Mandatory for the advance HW renderer effect. Unfortunately Mesa LLVMPIPE/SWR renderers doesn't support this extension.