buildcfg: Get rid of PHASE1_OR_PHASE2 #define.

This was only ever used for build of the "shareware" WAD and has not
been relevant for a long time now.

buildcfg.txt

@@ -16,14 +16,9 @@
 #endif
 
 #ifdef PHASE2
-#define PHASE1_OR_PHASE2
 #undef PHASE1
 #endif
 
-#ifdef PHASE1
-#define PHASE1_OR_PHASE2
-#endif
-
 ; List of levels
 [levels]
 
@@ -584,6 +579,9 @@ M_DOOM   13 -16
 #endif
 #endif
 
+; Used both in phase 2 and phase 1 (E4):
+INTERPIC	0	0
+
 #ifdef PHASE2
 HELP	0	0
 #endif
@@ -1096,11 +1094,6 @@ CWILV31 = DMWILV31
 
 #endif /* #ifdef PHASE2 */
 
-#ifdef PHASE1_OR_PHASE2
-; interpic is used by ultimate doom and doom2
-INTERPIC	0	0
-#endif
-
 ; sprites list
 
 [sprites]