fix savegamename not prepending srb2home to itself for custom mods using their own gamedata files

src/dehacked.c

@@ -11,6 +11,7 @@
 /// \brief Load dehacked file and change tables and text
 
 #include "doomdef.h"
+#include "d_main.h" // for srb2home
 #include "g_game.h"
 #include "sounds.h"
 #include "info.h"
@@ -3070,6 +3071,8 @@ static void readmaincfg(MYFILE *f)
 
 				strncpy(savegamename, timeattackfolder, sizeof (timeattackfolder));
 				strlcat(savegamename, "%u.ssg", sizeof(savegamename));
+				// can't use sprintf since there is %u in savegamename
+				strcatbf(savegamename, srb2home, PATHSEP);
 
 				gamedataadded = true;
 			}