use phosg namespace

src/PSOProtocol.hh

@@ -56,12 +56,12 @@ RetT& check_size_generic(
     size_t min_size,
     size_t max_size) {
   if (size < min_size) {
-    throw std::runtime_error(string_printf(
+    throw std::runtime_error(phosg::string_printf(
         "command too small (expected at least 0x%zX bytes, received 0x%zX bytes)",
         min_size, size));
   }
   if (size > max_size) {
-    throw std::runtime_error(string_printf(
+    throw std::runtime_error(phosg::string_printf(
         "command too large (expected at most 0x%zX bytes, received 0x%zX bytes)",
         max_size, size));
   }