Fix white flash levelshot bug in OpenGL1

If you tried to draw the last loaded image, gl texture 0 (which is appearently white)
was used because renderer thought the image was already bound.

Why OpenGL1 renderer binds texture 0, I have no idea. It's been removed from OpenGL2.

code/renderergl1/tr_image.c

@@ -900,6 +900,8 @@ image_t *R_CreateImage( const char *name, byte *pic, int width, int height,
 	qglTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, glWrapClampMode );
 	qglTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, glWrapClampMode );
 
+	// FIXME: this stops fog from setting border color?
+	glState.currenttextures[glState.currenttmu] = 0;
 	qglBindTexture( GL_TEXTURE_2D, 0 );
 
 	if ( image->TMU == 1 ) {