Make PrintTo functions static inline in perf_tests.cpp for better encapsulation. Add missing <ostream> include.

Author: allnes

modules/core/performance/tests/perf_tests.cpp

@@ -5,6 +5,7 @@
 #include <filesystem>
 #include <fstream>
 #include <memory>
+#include <ostream>
 #include <stdexcept>
 #include <string_view>
 #include <vector>
@@ -98,7 +99,7 @@ struct ParamTestCase {
   std::string expected_output;
 };
 
-inline void PrintTo(const ParamTestCase& param, std::ostream* os) {
+static inline void PrintTo(const ParamTestCase& param, std::ostream* os) {
   *os << "{ input = " << static_cast<int>(param.input) << ", expected = " << param.expected_output << " }";
 }
 
@@ -122,7 +123,7 @@ struct TaskTypeTestCase {
   std::string label;
 };
 
-inline void PrintTo(const TaskTypeTestCase& param, std::ostream* os) {
+static inline void PrintTo(const TaskTypeTestCase& param, std::ostream* os) {
   *os << "{ type = " << static_cast<int>(param.type) << ", expected = " << param.expected << ", label = " << param.label
       << " }";
 }