Move transport declarations into transport.h.

There are a few cloexec issues in here as an added bonus.

Change-Id: I1699d719d733f47878bdba0454230cf5ab6a60b6
diff --git a/adb/adb_main.c b/adb/adb_main.c
index 57a15dd..f8475c7 100644
--- a/adb/adb_main.c
+++ b/adb/adb_main.c
@@ -21,10 +21,12 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "sysdeps.h"
+
 #include "adb.h"
 #include "adb_auth.h"
 #include "adb_listeners.h"
-#include "sysdeps.h"
+#include "transport.h"
 
 #if !ADB_HOST
 #include <getopt.h>