recovery: Only show tests in eng builds

Change-Id: If783711ecd0d20728ec27ebc572b57e6d9bee760
diff --git a/common.h b/common.h
index a524a41..bc2c07b 100644
--- a/common.h
+++ b/common.h
@@ -36,3 +36,5 @@
 extern const char* reason;
 
 bool is_ro_debuggable();
+
+std::string get_build_type();