make savegamename in doomdef.h an extern, put the actual definition in d_main.c

(cherry picked from commit 89cd756cd83e4a03a34d1f16da18142d8167d889)

src/d_main.c

@@ -143,6 +143,8 @@ boolean advancedemo;
 INT32 debugload = 0;
 #endif
 
+char savegamename[256];
+
 #ifdef _arch_dreamcast
 char srb2home[256] = "/cd";
 char srb2path[256] = "/cd";

src/doomdef.h

@@ -506,7 +506,7 @@ void CONS_Debug(INT32 debugflags, const char *fmt, ...) FUNCDEBUG;
 
 // Things that used to be in dstrings.h
 #define SAVEGAMENAME "srb2sav"
-char savegamename[256];
+extern char savegamename[256];
 
 // m_misc.h
 #ifdef GETTEXT