Fix annoying GCC warnings in helloworld

This possibly fixes compile errors on MinGW (undefined size_t, etc).
Fix compile error in sampgdk.rc on MinGW

MinGW wanted all 4 version components to be there.
Add SAMPGDK_VERSION_SERVER

It is included in the DLL version as well as in SAMPGDK_VERSION_ID,
but not in SAMPGDK_VERSION or SAMPGDK_VERSION_STRING.
Include *all* version numbers in SAMPGDK_VERSION_STRING