core/core: Replace includes with forward declarations where applicable

The follow-up to e2457418dae19b889b2ad85255bb95d4cd0e4bff, which
replaces most of the includes in the core header with forward declarations.

This makes it so that if any of the headers the core header was
previously including change, then no one will need to rebuild the bulk
of the core, due to core.h being quite a prevalent inclusion.

This should make turnaround for changes much faster for developers.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/core/perf_stats.cpp b/src/core/perf_stats.cpp
index 93d23de21..7d95816fe 100644
--- a/src/core/perf_stats.cpp
+++ b/src/core/perf_stats.cpp
@@ -40,7 +40,7 @@ void PerfStats::EndGameFrame() {
     game_frames += 1;
 }
 
-PerfStats::Results PerfStats::GetAndResetStats(microseconds current_system_time_us) {
+PerfStatsResults PerfStats::GetAndResetStats(microseconds current_system_time_us) {
     std::lock_guard<std::mutex> lock(object_mutex);
 
     const auto now = Clock::now();
@@ -49,7 +49,7 @@ PerfStats::Results PerfStats::GetAndResetStats(microseconds current_system_time_
 
     const auto system_us_per_second = (current_system_time_us - reset_point_system_us) / interval;
 
-    Results results{};
+    PerfStatsResults results{};
     results.system_fps = static_cast<double>(system_frames) / interval;
     results.game_fps = static_cast<double>(game_frames) / interval;
     results.frametime = duration_cast<DoubleSecs>(accumulated_frametime).count() /