RFR (XS): 8145674: Fix includes and forward declarations in g1Remset files

[Thomas Schatzl]

Hi Volker,

On Fri, 2015-12-18 at 15:23 +0100, Volker Simonis wrote:
> OK, you convinced me :)
> 
> Thumbs up!
> 

  thanks to you and Stefan for the reviews.

Thomas