SYSCF bits

(This covers some thing that Pat found and some things I found while working
on those.)
Unscramble duplicate use of GREPPATH and GDBPATH symbols.
Add some more info to config.h.
Make missing SYSCF_FILE a fatal error.
Make a parse error in SYSCF_FILE a fatal error.
Rename PANICTRACE_GLIBC (et al) to PANICTRACE_LIBC (et al) since FreeBSD
 and Mac OS X (at least) also implement the needed API.
Allow SYSCF_FILE to be unreadable by the user (for setgid installs).
If SYSCF, do NOT fall back to the compiled in WIZARD account.
Put WIZARD into sysopt and remove special cases in authorize_wizard_mode().

include/extern.h

@@ -742,7 +742,7 @@ E void FDECL(unlock_file, (const char *));
 #ifdef USER_SOUNDS
 E boolean FDECL(can_read_file, (const char *));
 #endif
-E void FDECL(read_config_file, (const char *, int));
+E boolean FDECL(read_config_file, (const char *, int));
 E void FDECL(check_recordfile, (const char *));
 #if defined(WIZARD)
 E void NDECL(read_wizkit);
@@ -2357,6 +2357,9 @@ E void NDECL(port_help);
 E void FDECL(sethanguphandler, (void (*)(int)));
 E boolean NDECL(authorize_wizard_mode);
 E boolean FDECL(check_user_string, (char *));
+# ifdef SYSCF_FILE
+E void NDECL(assure_syscf_file);
+# endif
 #endif /* UNIX */
 
 /* ### unixtty.c ### */
@@ -2384,6 +2387,9 @@ E int NDECL(dosh);
 # if defined(SHELL) || defined(DEF_PAGER) || defined(DEF_MAILREADER)
 E int FDECL(child, (int));
 # endif
+# ifdef PANICTRACE
+E boolean FDECL(file_exists, (const char *));
+# endif
 #endif /* UNIX */
 
 /* ### unixres.c ### */