The first crude version of tracing across libraries

- the patch will be sliced later
diff --git a/sysdeps/linux-gnu/breakpoint.c b/sysdeps/linux-gnu/breakpoint.c
index 58eac8d..1012447 100644
--- a/sysdeps/linux-gnu/breakpoint.c
+++ b/sysdeps/linux-gnu/breakpoint.c
@@ -7,6 +7,7 @@
 #include "arch.h"
 #include "breakpoint.h"
 #include "proc.h"
+#include "library.h"
 
 #ifdef ARCH_HAVE_ENABLE_BREAKPOINT
 extern void arch_enable_breakpoint(pid_t, struct breakpoint *);