GL: Clamp number of MRT targets.

src/renderer_gl.cpp

@@ -2331,7 +2331,9 @@ BX_TRACE("%d, %d, %d, %s", _array, _srgb, _mipAutogen, getName(_format) );
 				||  s_extension[Extension::EXT_draw_buffers  ].m_supported
 				||  s_extension[Extension::WEBGL_draw_buffers].m_supported)
 				{
-					g_caps.limits.maxFBAttachments = uint8_t(bx::uint32_min(glGet(GL_MAX_DRAW_BUFFERS)
+					g_caps.limits.maxFBAttachments = uint8_t(bx::uint32_clamp(
+							  glGet(GL_MAX_DRAW_BUFFERS)
+							, 1
 							, BGFX_CONFIG_MAX_FRAME_BUFFER_ATTACHMENTS)
 							);
 				}