Begin moving code from adb to libadb.

Much of adb is duplicated in bootable/recovery/minadb and fastboot.
Changes made to adb rarely get ported to the other two, so the trees
have diverged a bit. We'd like to stop this because it is a
maintenance nightmare, but the divergence makes this difficult to do
all at once. For now, we will start small by moving common files into
a static library. Hopefully some day we can get enough of adb in here
that we no longer need minadb.

Bug: 17626262
Change-Id: Ic8d5653bfcc0fec4e1acbece124402355084b864
diff --git a/transport.h b/transport.h
index 992e052..c1b8ff3 100644
--- a/transport.h
+++ b/transport.h
@@ -17,10 +17,19 @@
 #ifndef __TRANSPORT_H
 #define __TRANSPORT_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* convenience wrappers around read/write that will retry on
 ** EINTR and/or short read/write.  Returns 0 on success, -1
 ** on error or EOF.
 */
 int readx(int fd, void *ptr, size_t len);
 int writex(int fd, const void *ptr, size_t len);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif   /* __TRANSPORT_H */