libbinder: save space for optional config options.

Previously, we required user and userdebug vesions of this
library to be the same, but now we can save some space.

Bug: N/A
Test: Android's SDK finalization script passes
Change-Id: I6a5f2a04ea8bf4ff2253ad052ea757ce2031a27c
diff --git a/libs/binder/Binder.cpp b/libs/binder/Binder.cpp
index 3e49656..0f4a6ca 100644
--- a/libs/binder/Binder.cpp
+++ b/libs/binder/Binder.cpp
@@ -58,15 +58,15 @@
 
 // global b/c b/230079120 - consistent symbol table
 #ifdef BINDER_RPC_DEV_SERVERS
-bool kEnableRpcDevServers = true;
+constexpr bool kEnableRpcDevServers = true;
 #else
-bool kEnableRpcDevServers = false;
+constexpr bool kEnableRpcDevServers = false;
 #endif
 
 #ifdef BINDER_ENABLE_RECORDING
-bool kEnableRecording = true;
+constexpr bool kEnableRecording = true;
 #else
-bool kEnableRecording = false;
+constexpr bool kEnableRecording = false;
 #endif
 
 // Log any reply transactions for which the data exceeds this size