Helm fails to run when the Core OpenGL profile is used

[bepzi]

Commit e98fd4a introduced changes to the OpenGL module in order to fix builds of Vitalium, but ironically, I think these changes broke Helm, which I'm refactoring and porting to JUCE 6. The problem is caused by using the Core OpenGL profile:

JUCE/modules/juce_opengl/native/juce_OpenGL_linux_X11.h

Lines 167 to 176 in b1a9246

	bool initialiseOnRenderThread (OpenGLContext& c)
	{
	XWindowSystemUtilities::ScopedXLock xLock;
	PFNGLXCREATECONTEXTATTRIBSARBPROC createContextAttribs;
	int attribs[] = {
	GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
	GLX_CONTEXT_MINOR_VERSION_ARB, 2,
	GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_CORE_PROFILE_BIT_ARB,
	0
	};

Where if you build and run Helm with this fork of JUCE, it crashes on startup due to misusing glVertexAttribPointer:

./helm

# ...

Message: GL_INVALID_OPERATION in glVertexAttribPointer(no array object bound)
Source: API
Type: Error
ID: 2
Severity: High

Message: GL_INVALID_OPERATION in glVertexAttribPointer(no array object bound)
Source: API
Type: Error
ID: 2
Severity: High

Message: GL_INVALID_OPERATION in glDrawElements(no VAO bound)
Source: API
Type: Error
ID: 2
Severity: High

helm: ../../../src/editor_components/open_gl_background.cpp:151: virtual void OpenGLBackground::render(juce::OpenGLContext&): Assertion `glGetError() == 0' failed.
zsh: abort (core dumped)  ./standalone/builds/linux/build/helm

(I'm a bit rusty with my OpenGL, so I'm afraid I can't diagnose exactly why the Core profile rejects this until I read up on it some more.)

If instead of GLX_CONTEXT_CORE_PROFILE_BIT_ARB, you use GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB, Helm runs normally without errors or warnings.

Now, obviously the real problem here is Helm's OpenGL code, not this fork of JUCE. I intend to eventually look at it and figure out why it's not working, and rewrite it so that it's compliant with the Core profile. But I figured it was worth mentioning because it seems like a deviation from vanilla JUCE (Helm works fine if you replace juce_OpenGL_linux_X11.h with the current vanilla version), so this change might be breaking for other plugins with dubious OpenGL code.