Create bootloader_message static library.

bootloader_messages merges bootloader_message_writer
and bootloader.cpp, so we can use the same library to
manage bootloader_message in normal boot and recovery mode.

Bug: 29582118

Change-Id: I9efdf776ef8f02b53911ff43a518e035e0c29618
(cherry picked from commit 2f272c0551f984e83bc5abaf240e0dddb38a3326)
diff --git a/uncrypt/uncrypt.cpp b/uncrypt/uncrypt.cpp
index c77e987..8b4d8ef 100644
--- a/uncrypt/uncrypt.cpp
+++ b/uncrypt/uncrypt.cpp
@@ -111,7 +111,7 @@
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
-#include <bootloader_message_writer.h>
+#include <bootloader_message/bootloader_message.h>
 #include <cutils/android_reboot.h>
 #include <cutils/sockets.h>
 #include <fs_mgr.h>