Replacing format string with one appropriate for 32-bit or 64-bit size.

Change-Id: I280f38ce000a5231795953b251ba2123545903ae
(cherry picked from commit 37920d9d6ea3f29f9e8d910fa0b41260159cb6f7)
diff --git a/kernel_module_loader.cpp b/kernel_module_loader.cpp
index 1a4786c..aadfd93 100644
--- a/kernel_module_loader.cpp
+++ b/kernel_module_loader.cpp
@@ -90,7 +90,7 @@
 	std::string kernel_module_file = "/proc/modules";
 	if (TWFunc::read_file(kernel_module_file, loaded_modules) < 0)
 		LOGINFO("failed to get loaded kernel modules\n");
-	LOGINFO("number of modules loaded by init: %lu\n", loaded_modules.size());
+	LOGINFO("number of modules loaded by init: %zu\n", loaded_modules.size());
 	if (loaded_modules.size() == 0)
 		return kernel_modules;
 	for (auto&& module_line:loaded_modules) {