add gps to checked globals

Author: ab9rf

docs/changelog.txt

@@ -61,6 +61,7 @@ Template for new versions:
 ## Fixes
 
 ## Misc Improvements
+- Core: added ``gps`` (``graphicst``) to the set of globals whose sizes must agree for DFHack to pass initialization checks
 
 ## Documentation
 

library/Core.cpp

@@ -1682,6 +1682,7 @@ bool Core::InitMainThread() {
             { "world", sizeof(df::world) },
             { "game", sizeof(df::gamest) },
             { "plotinfo", sizeof(df::plotinfost) },
+            { "gps", sizeof(df::graphic) },
         };
 
         for (auto& gte : *df::global::global_table)