If (use-modules (dbi dbi)) is called multiple times, then guile
will crash in various strange ways, often during garbage-collection.
Thus, avoid initializaing more than once.

From: Linas Vepstas <linasvepstas@gmail.com>

---
 src/guile-dbi.c |    3 +++
 1 file changed, 3 insertions(+)

Index: guile-dbi-2.0.0/src/guile-dbi.c
===================================================================
--- guile-dbi-2.0.0.orig/src/guile-dbi.c	2008-09-15 13:03:05.000000000 -0500
+++ guile-dbi-2.0.0/src/guile-dbi.c	2008-09-15 13:19:36.000000000 -0500
@@ -295,6 +295,9 @@ init_db_handle_type(void)
 void 
 init_dbi(void)
 {
+  static int is_inited = 0;
+  if (is_inited) return;
+  is_inited = 1;
   init_db_handle_type();
 
 #ifndef SCM_MAGIC_SNARFER