Support for AMD_transform_feedback3_lines_triangles.

Just adding the extension to the list, otherwise not much to do.

doc/opengl-support.dox

@@ -257,6 +257,7 @@ Extension                                   | Status
 
 Extension                                   | Status
 ------------------------------------------- | ------
+@extension{AMD,transform_feedback3_lines_triangles} | done (nothing to do)
 @extension{AMD,vertex_shader_layer}         | done (shading language only)
 @extension{AMD,shader_trinary_minmax}       | done (shading language only)
 @extension{ATI,texture_mirror_once}         | done (GL 4.4 subset)

src/Magnum/Context.cpp

@@ -65,6 +65,7 @@ const std::vector<Extension>& Extension::extensions(Version version) {
     static const std::vector<Extension> empty;
     #ifndef MAGNUM_TARGET_GLES
     static const std::vector<Extension> extensions{
+        _extension(GL,AMD,transform_feedback3_lines_triangles),
         _extension(GL,AMD,vertex_shader_layer),
         _extension(GL,AMD,shader_trinary_minmax),
         _extension(GL,ARB,robustness),

src/Magnum/Extensions.h

@@ -80,6 +80,7 @@ namespace GL {
     #ifndef MAGNUM_TARGET_GLES
     #line 1
     namespace AMD {
+        _extension(GL,AMD,transform_feedback3_lines_triangles, GL210, None) // #397
         _extension(GL,AMD,vertex_shader_layer,          GL210,  None) // #417
         _extension(GL,AMD,shader_trinary_minmax,        GL210,  None) // #428
     } namespace ARB {