Remove EXPAND/STRINGIFY macros.

This reverts commit 8be0f39fec7f26164fd0791ff6d15bde65fc849c to reland
the change that removes EXPAND/STRINGIFY macros.

It's error-prone by putting anything into a string (e.g.
EXPAND(RECOVERY_API_VERSION) would become "RECOVER_API_VERSION" if we
forgot to pass -DRECOVERY_API_VERSION=3).

The initial attempt put RECOVERY_API_VERSION into common.h, which might
be included by device-specific codes but without defining that when
compiling the module. This CL avoids the issue by using a constant
in the header, with a static_assert in recovery.cpp that guards the
consistency.

Test: recovery_component_test
Test: Sideload OTAs on bullhead and sailfish respectively.
Change-Id: I12af3f73392a85554ba703f04970ec9d984ccbaa
diff --git a/common.h b/common.h
index 62fb132..8b336f8 100644
--- a/common.h
+++ b/common.h
@@ -22,8 +22,9 @@
 
 #include <string>
 
-#define STRINGIFY(x) #x
-#define EXPAND(x) STRINGIFY(x)
+// Not using the command-line defined macro here because this header could be included by
+// device-specific recovery libraries. We static assert the value consistency in recovery.cpp.
+static constexpr int kRecoveryApiVersion = 3;
 
 class RecoveryUI;