LibGL: Implement glActiveTextureARB()

This is the equivalent of glActiveTexture() before it got promoted to
the OpenGL core specification. It is needed by glquake to enable the
multitexturing render path.

Userland/Libraries/LibGL/GL/gl.h

@@ -577,6 +577,7 @@ GLAPI void glTexEnvf(GLenum target, GLenum pname, GLfloat param);
 GLAPI void glTexEnvi(GLenum target, GLenum pname, GLint param);
 GLAPI void glBindTexture(GLenum target, GLuint texture);
 GLAPI GLboolean glIsTexture(GLuint texture);
+GLAPI void glActiveTextureARB(GLenum texture);
 GLAPI void glActiveTexture(GLenum texture);
 GLAPI void glGetBooleanv(GLenum pname, GLboolean* data);
 GLAPI void glGetDoublev(GLenum pname, GLdouble* params);

Userland/Libraries/LibGL/GLTexture.cpp

@@ -52,8 +52,11 @@ GLboolean glIsTexture(GLuint texture)
     return g_gl_context->gl_is_texture(texture);
 }
 
-// Note: This is an _extremely_ misleading API name. This sets the active
-// texture unit, NOT the active texture itself...
+void glActiveTextureARB(GLenum texture)
+{
+    glActiveTexture(texture);
+}
+
 void glActiveTexture(GLenum texture)
 {
     g_gl_context->gl_active_texture(texture);