Relax the requirement to provide geometry shader support to accept a 3.2+ compatibility context as well. While the compatibility profile functionality is not 100% identical to the EXT/ARB functionality, the extent to which SFML makes use of geometry shaders should not pose any serious problems to a developer who is aware of the subtle differences. The current geometry shader example already requires GLSL 1.50 which was only available in OpenGL 3.2+. (Closes #1768)

src/SFML/Graphics/Shader.cpp

@@ -815,7 +815,7 @@ bool Shader::isGeometryAvailable()
         // Make sure that extensions are initialized
         sf::priv::ensureExtensionsInit();
 
-        available = isAvailable() && GLEXT_geometry_shader4;
+        available = isAvailable() && (GLEXT_geometry_shader4 || GLEXT_GL_VERSION_3_2);
     }
 
     return available;