OpenGL2: Use CPU vertex animation if too few vertex attributes

OpenGL ES has a minimum of 8 vertex attributes while desktop OpenGL has
a minimum of 16. Vertex animation uses attributes 10 to 12.

code/renderergl2/tr_init.c

@@ -279,6 +279,9 @@ static void InitOpenGL( void )
 		qglGetIntegerv( GL_MAX_TEXTURE_IMAGE_UNITS, &temp );
 		glConfig.numTextureUnits = temp;
 
+		qglGetIntegerv( GL_MAX_VERTEX_ATTRIBS, &temp );
+		glRefConfig.maxVertexAttribs = temp;
+
 		// reserve 160 components for other uniforms
 		qglGetIntegerv( GL_MAX_VERTEX_UNIFORM_COMPONENTS, &temp );
 		glRefConfig.glslMaxAnimatedBones = Com_Clamp( 0, IQM_MAX_JOINTS, ( temp - 160 ) / 16 );