handle usb serial devices via ucomnames

Index: conserver/cutil.h
--- conserver/cutil.h.orig
+++ conserver/cutil.h
@@ -223,3 +223,5 @@ extern int SSLVerifyCallback(int, X509_STORE_CTX *);
 extern int FileSSLAccept(CONSFILE *);
 extern int FileCanSSLAccept(CONSFILE *, fd_set *, fd_set *);
 #endif
+extern char *get_ucomnames(void);
+extern char *find_ucom(const char *, const char *);
