fix: cannot initialize a parameter of type 'GLuint' (aka 'unsigned int')
with an rvalue of type 'std::nullptr_t'

Index: codemp/rd-rend2/tr_init.cpp
--- codemp/rd-rend2/tr_init.cpp.orig
+++ codemp/rd-rend2/tr_init.cpp
@@ -1862,7 +1862,7 @@ static void R_InitStaticConstants()
 		GL_UNIFORM_BUFFER, tr.defaultShaderInstanceUboOffset, sizeof(shaderInstanceBlock), &shaderInstanceBlock);
 	alignedBlockSize += (sizeof(ShaderInstanceBlock) + alignment) & ~alignment;
 
-	qglBindBuffer(GL_UNIFORM_BUFFER, NULL);
+	qglBindBuffer(GL_UNIFORM_BUFFER, 0);
 	glState.currentGlobalUBO = -1;
 
 	GL_CheckErrors();
