Add extern "C" to all the headers.

Change-Id: Idc249ff1b199b7c455f90092ff2c8a48b539faf4
diff --git a/minadbd/fdevent.h b/minadbd/fdevent.h
index a0ebe2a..38b08cc 100644
--- a/minadbd/fdevent.h
+++ b/minadbd/fdevent.h
@@ -19,6 +19,10 @@
 
 #include <stdint.h>  /* for int64_t */
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* events that may be observed */
 #define FDE_READ              0x0001
 #define FDE_WRITE             0x0002
@@ -79,5 +83,8 @@
     void *arg;
 };
 
+#ifdef __cplusplus
+}
+#endif
 
 #endif