OpenGL: Drop the dead Intel dual-source check, fix the ES3 init fallback

The Intel workaround sscanf'd "Build %d.%d.%d.%d" against glGetString(GL_VERSION),
which reads like "4.5.0 - Build 26.20.100.7870" - sscanf literals have to match
from the start, so it never returned 4 and HasIntelDualSrcBug was never consulted.
It's been inert since it was written, and the drivers it targeted are long gone.
Removing it orphaned the two helpers, so those go too.

Separately, when gl3stubInit() fails we left ver[0] at 3 while clearing GLES3.
Extension enumeration keys off the version, not the flag, so it went on to call
glGetStringi - one of the very entry points whose absence makes gl3stubInit()
fail. Drop back to 2.0 on that path, like the branch above it already does, and
null-check what glGetStringi hands back.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Vd8ntC2brCUtCrDJMqLbs8

Common/GPU/OpenGL/GLFeatures.cpp

@@ -306,6 +306,13 @@ bool CheckGLExtensions() {
 			// Otherwise, let's trust GL_MAJOR_VERSION.  Note that Mali is intentionally not banned here.
 			if (gl_extensions.ver[0] >= 3) {
 				gl_extensions.GLES3 = gl3stubInit();
+				if (!gl_extensions.GLES3) {
+					// We failed to load the ES3 entry points, so we can't use any of them - including
+					// glGetStringi below, which is one of the ones gl3stubInit() checks for. Drop back
+					// to 2.0 so nothing downstream keys off the version and calls into a null pointer.
+					gl_extensions.ver[0] = 2;
+					gl_extensions.ver[1] = 0;
+				}
 			}
 		}
 #else
@@ -331,6 +338,9 @@ bool CheckGLExtensions() {
 		g_set_gl_extensions.clear();
 		for (GLint i = 0; i < numExtensions; ++i) {
 			const char *ext = (const char *)glGetStringi(GL_EXTENSIONS, i);
+			if (!ext) {
+				continue;
+			}
 			g_set_gl_extensions.insert(ext);
 			g_all_gl_extensions += ext;
 			g_all_gl_extensions += " ";

Common/GPU/OpenGL/thin3d_gl.cpp

@@ -534,26 +534,6 @@ private:
 	PresentMode requestedPresentMode_{};
 };
 
-static constexpr int MakeIntelSimpleVer(int v1, int v2, int v3) {
-	return (v1 << 16) | (v2 << 8) | v3;
-}
-
-static bool HasIntelDualSrcBug(const int versions[4]) {
-	// Intel uses a confusing set of at least 3 version numbering schemes.  This is the one given to OpenGL.
-	switch (MakeIntelSimpleVer(versions[0], versions[1], versions[2])) {
-	case MakeIntelSimpleVer(9, 17, 10):
-	case MakeIntelSimpleVer(9, 18, 10):
-		return false;
-	case MakeIntelSimpleVer(10, 18, 10):
-		return versions[3] < 4061;
-	case MakeIntelSimpleVer(10, 18, 14):
-		return versions[3] < 4080;
-	default:
-		// Older than above didn't support dual src anyway, newer should have the fix.
-		return false;
-	}
-}
-
 OpenGLContext::OpenGLContext(bool canChangeSwapInterval) : renderManager_(frameTimeHistory_) {
 	if (gl_extensions.IsGLES) {
 		if (gl_extensions.OES_packed_depth_stencil || gl_extensions.OES_depth24) {
@@ -647,17 +627,6 @@ OpenGLContext::OpenGLContext(bool canChangeSwapInterval) : renderManager_(frameT
 	if (!gl_extensions.VersionGEThan(3, 0, 0)) {
 		// Don't use this extension on sub 3.0 OpenGL versions as it does not seem reliable.
 		bugs_.Infest(Bugs::DUAL_SOURCE_BLENDING_BROKEN);
-	} else if (caps_.vendor == GPUVendor::VENDOR_INTEL) {
-		// Note: this is for Intel drivers with GL3+.
-		// Also on Intel, see https://github.com/hrydgard/ppsspp/issues/10117
-		// TODO: Remove entirely sometime reasonably far in driver years after 2015.
-		const std::string ver = OpenGLContext::GetInfoString(Draw::InfoField::APIVERSION);
-		int versions[4]{};
-		if (sscanf(ver.c_str(), "Build %d.%d.%d.%d", &versions[0], &versions[1], &versions[2], &versions[3]) == 4) {
-			if (HasIntelDualSrcBug(versions)) {
-				bugs_.Infest(Bugs::DUAL_SOURCE_BLENDING_BROKEN);
-			}
-		}
 	}
 
 #if PPSSPP_ARCH(ARMV7)