fix: use has_root_path() for cross-platform plugin library path check

Co-authored-by: irozzo-1A <iacopo@sysdig.com>
Signed-off-by: Leonardo Grasso <me@leonardograsso.com>

Author: 2 people

userspace/falco/configuration.h

@@ -402,8 +402,7 @@ struct convert<falco_configuration::plugin_config> {
 		}
 		rhs.m_library_path = node["library_path"].as<std::string>();
 		if(!rhs.m_library_path.empty() &&
-		   !std::filesystem::path(rhs.m_library_path).is_absolute() &&
-		   rhs.m_library_path.at(0) != '/') {
+		   !std::filesystem::path(rhs.m_library_path).has_root_path()) {
 			// Relative path: resolve against the plugins directory
 			// and verify the result stays within it.
 			auto full_path = std::filesystem::path(FALCO_ENGINE_PLUGINS_DIR) / rhs.m_library_path;