(dflt_econfig): New.

(emp_config): Use it when argument is NULL.  This simplifies callers
except pconfig's main(), which now has to suppress reading the default
file.  Also fix callers to check the return value.  Previously, a typo
could easily start a grossly misconfigured program, with potentially
disastrous results.

src/lib/global/path.c

@@ -33,7 +33,8 @@
  */
 
 #include "gamesdef.h"
-#include "misc.h"
+
+char dflt_econfig[] = EMPDIR "/data/econfig";
 
 char *infodir	= EMPDIR "/info.nr";
 char *datadir	= EMPDIR "/data";