Ports+LibGL: Replace LibGL context check by ScummVM patch

According to the OpenGL spec, invoking functions without an active
context results in undefined behavior. Since ScummVM seems to be the
only port having issues with our behavior, patch their code instead.

Ports/scummvm/patches/0001-Prevent-call-to-glGetIntegerv-without-context.patch

@@ -0,0 +1,30 @@
+From c758a59b2b26e3ab22c4fbcba6c83e0b385b86ce Mon Sep 17 00:00:00 2001
+From: Jelle Raaijmakers <[email protected]>
+Date: Wed, 12 Jan 2022 13:41:39 +0100
+Subject: [PATCH] Prevent call to `glGetIntegerv` without context
+
+This call to `SDL_GL_GetAttribute` happens when switching from the
+launcher to the game, when no GL context may exist. This caused Grim
+Fandango to crash almost immediately.
+
+Since this is for MSAA which we do not yet support, patch it out.
+---
+ backends/graphics3d/openglsdl/openglsdl-graphics3d.cpp | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/backends/graphics3d/openglsdl/openglsdl-graphics3d.cpp b/backends/graphics3d/openglsdl/openglsdl-graphics3d.cpp
+index d5c034f..8a4e3ff 100644
+--- a/backends/graphics3d/openglsdl/openglsdl-graphics3d.cpp
++++ b/backends/graphics3d/openglsdl/openglsdl-graphics3d.cpp
+@@ -185,7 +185,7 @@ void OpenGLSdlGraphics3dManager::setupScreen() {
+ // (or not bridged in Emscripten?). This forces a windows reset.
+ currentSamples = -1;
+ #else
+- SDL_GL_GetAttribute(SDL_GL_MULTISAMPLESAMPLES, &currentSamples);
++ currentSamples = -1;
+ #endif
+
+ // When rendering to a framebuffer, MSAA is enabled on that framebuffer, not on the screen
+-- 
+2.32.0
+

Userland/Libraries/LibGL/GLContext.h

@@ -15,16 +15,6 @@
 
 namespace GL {
 
-#define VERIFY_CURRENT_CONTEXT() \
- if (!g_gl_context) { \
- return; \
- }
-
-#define VERIFY_CURRENT_CONTEXT_OR_VALUE(value) \
- if (!g_gl_context) { \
- return value; \
- }
-
 class GLContext {
 public:
  virtual ~GLContext();

Userland/Libraries/LibGL/GLUtils.cpp

@@ -67,7 +67,6 @@ void glViewport(GLint x, GLint y, GLsizei width, GLsizei height)
 
 GLenum glGetError()
 {
- VERIFY_CURRENT_CONTEXT_OR_VALUE(GL_NONE);
  return g_gl_context->gl_get_error();
 }
 
@@ -118,7 +117,6 @@ void glGetFloatv(GLenum pname, GLfloat* params)
 
 void glGetIntegerv(GLenum pname, GLint* data)
 {
- VERIFY_CURRENT_CONTEXT();
  g_gl_context->gl_get_integerv(pname, data);
 }