Looks like you don't have the GG files in the expected location relative to the FreeOrion solution, for some reason.
Then this would have to be true for much more than the GG files. It is popping up for pretty much everything it tries to grab when building the solution.
I'm a bit confused about the "trunk" being there; it shouldn't be if you've just opened the SDK and updated from SVN. Did you just "update" the FreeOrion directory as present in the SDK, or did you do a new checkout over top and in a new location? Regardless, I suggest trying opening the SDK and updating and rebuilding again.
I double checked this. The trunk is gone now (so I must have checked out on top of the SDK the first time). But still, getting the same issues. Here is what I did:
1. Started with the SDK (FreeOrion_Win32_MSVS2010_SDK_3_Oct_2011.zip). It's been extracted to the C:, away from any program files directory
2. Went to update with Tortoise. Before I could, I had to choose "SVN upgrade working copy"
3. I then run SVN Update - Generally ok, but has one "Tree conflict": C:\FreeOrion\FreeOrion\msvc2008. Everything else is just added (most of the line items) or restored (some line items)
4. I open the solution file located in msvc2010, and try to build. I am flooded with errors saying that the file or directory could not be found (not just limited to GG).
Maybe I have done something wrong with the extraction of the SDK, or maybe I am missing a step?Edit:
I did check through the solution window, it seems to be based mostly around these three roots: GG, log4cpp, and boost. The first few lines are:
1>------ Build started: Project: GiGi, Configuration: Debug Win32 ------
2>------ Build started: Project: log4cpp, Configuration: Debug Win32 ------
1>cl : Command line error D8016: '/Ox' and '/RTC1' command-line options are incompatible
3>------ Build started: Project: GiGiOgre, Configuration: Debug Win32 ------
From here, it does into the whole list of fatal error, file not found errors.