Update libregexp with recent bug fixes from Plan 9.
diff --git a/src/libregexp/lib9.h b/src/libregexp/lib9.h
index d022656..07a1f97 100644
--- a/src/libregexp/lib9.h
+++ b/src/libregexp/lib9.h
@@ -1,6 +1,2 @@
-#include <fmt.h>
-#include <setjmp.h>
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-
+#include <u.h>
+#include <libc.h>