Revert "Remove EXPAND/STRINGIFY macros."

This reverts commit ec9706738f35a859f66fd0758b73381055804f63.

Reason for revert: It's not a good idea to put RECOVERY_API_VERSION in
common.h, which might be included by device-specific codes (but with
RECOVERY_API_VERSION undefined).

Change-Id: I9feb9c64a5af3e9165164622a59b043aa28a8b8c
diff --git a/install.cpp b/install.cpp
index 2cc0660..689f4a0 100644
--- a/install.cpp
+++ b/install.cpp
@@ -287,7 +287,7 @@
 
   *cmd = {
     binary,
-    std::to_string(kRecoveryApiVersion),
+    EXPAND(RECOVERY_API_VERSION),  // defined in Android.mk
     std::to_string(status_fd),
     path,
   };