Move d2x-rebirth/main/segment.cpp -> similar/main/segment.cpp

SConstruct

@@ -1562,6 +1562,7 @@ class DXXProgram(DXXCommon):
 'main/render.cpp',
 'main/robot.cpp',
 'main/scores.cpp',
+'main/segment.cpp',
 'main/slew.cpp',
 'main/songs.cpp',
 'main/state.cpp',
@@ -1905,7 +1906,6 @@ class D2XProgram(DXXProgram):
 'main/escort.cpp',
 'main/gamepal.cpp',
 'main/movie.cpp',
-'main/segment.cpp',
 'misc/physfsrwops.cpp',
 ]
 ],

similar/main/segment.cpp

@@ -15,6 +15,7 @@
 #include "segment.h"
 #include "physfsx.h"
 
+#if defined(DXX_BUILD_DESCENT_II)
 /*
  * reads a segment2 structure from a PHYSFS_file
  */
@@ -80,3 +81,4 @@ void dl_index_write(dl_index *di, PHYSFS_file *fp)
 	PHYSFSX_writeU8(fp, di->count);
 	PHYSFS_writeSLE16(fp, di->index);
 }
+#endif