Resolve full path to specified ctrl directory, before chdir

If a relative path to the ctrl directory is specified on the command-line
or in the SBBSCTRL environment variable, the loading of ctrl/*.ini would
fail after the changing of the working directory.

We should probably get replace all use of FULLPATH with _fullpath someday,
but for now, I just went with majority-rule.

src/sbbs3/jsexec.c

@@ -1456,6 +1456,9 @@ int main(int argc, char **argv, char** env)
 	strcpy(scfg.sys_inetaddr, "example.com");
 	scfg.prepped = true;
 #else
+	char relpath[PATH_MAX + 1];
+	SAFECOPY(relpath, scfg.ctrl_dir);
+	FULLPATH(scfg.ctrl_dir, relpath, sizeof scfg.ctrl_dir);
 	if(change_cwd && chdir(scfg.ctrl_dir)!=0)
 		fprintf(errfp,"!ERROR changing directory to: %s\n", scfg.ctrl_dir);