updater: Add a function to check first block

Add and register a function to check if the device has been remounted
since last update during incremental OTA. This function reads block 0
and executes before partition recovery for version >= 4.

Bug: 21124327
Change-Id: I8b915b9f1d4736b3609daa9d16bd123225be357f
diff --git a/updater/install.h b/updater/install.h
index 659c8b4..70e3434 100644
--- a/updater/install.h
+++ b/updater/install.h
@@ -19,6 +19,9 @@
 
 void RegisterInstallFunctions();
 
+// uiPrintf function prints msg to screen as well as logs
+void uiPrintf(State* state, const char* format, ...);
+
 static int make_parents(char* name);
 
 #endif