Allow the defining of an init file at build time

Since OpenBSD is unable to determine the pathname of a running process,
this allows us to specify the full path to flisp.boot. This will also
come in handy for system wide installs where you want flisp to live in
bin and flisp.boot to live in share or a similar location.

flmain.c

@@ -27,6 +27,9 @@ int main(int argc, char *argv[])
     fl_init(512*1024);
 
     fname_buf[0] = '\0';
+#ifdef INITFILE
+    strcat(fname_buf, INITFILE);
+#else
     value_t str = symbol_value(symbol("*install-dir*"));
     char *exedir = (str == UNBOUND ? NULL : cvalue_data(str));
     if (exedir != NULL) {
@@ -34,6 +37,7 @@ int main(int argc, char *argv[])
         strcat(fname_buf, PATHSEPSTRING);
     }
     strcat(fname_buf, "flisp.boot");
+#endif
 
     value_t args[2];
     fl_gc_handle(&args[0]);