turn recovery into a C++ binary

Change-Id: I423a23581048d451d53eef46e5f5eac485b77555
diff --git a/install.h b/install.h
index 5ebe160..1943f02 100644
--- a/install.h
+++ b/install.h
@@ -19,6 +19,10 @@
 
 #include "common.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT };
 // Install the package specified by root_path.  If INSTALL_SUCCESS is
 // returned and *wipe_cache is true on exit, caller should wipe the
@@ -26,4 +30,8 @@
 int install_package(const char *root_path, int* wipe_cache,
                     const char* install_file);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif  // RECOVERY_INSTALL_H_