mac-avcapture/legacy: Move comparison operator up

std::find is used in enumerate_frame_rates already, so the equality
operator is needed there. Until C++17 this is defined implicitly, but
since C++20 it's needed explicitly.

plugins/mac-avcapture/legacy/av-capture.mm

@@ -1548,6 +1548,16 @@ static media_frames_per_second convert(CMTime time_)
 
 using frame_rates_t = vector<pair<media_frames_per_second, media_frames_per_second>>;
 
+static bool operator==(const media_frames_per_second &a, const media_frames_per_second &b)
+{
+    return a.numerator == b.numerator && a.denominator == b.denominator;
+}
+
+static bool operator!=(const media_frames_per_second &a, const media_frames_per_second &b)
+{
+    return !(a == b);
+}
+
 static frame_rates_t enumerate_frame_rates(AVCaptureDevice *dev, const CMVideoDimensions *dims = nullptr)
 {
     frame_rates_t res;
@@ -1588,16 +1598,6 @@ static frame_rates_t enumerate_frame_rates(AVCaptureDevice *dev, const CMVideoDi
     return res;
 }
 
-static bool operator==(const media_frames_per_second &a, const media_frames_per_second &b)
-{
-    return a.numerator == b.numerator && a.denominator == b.denominator;
-}
-
-static bool operator!=(const media_frames_per_second &a, const media_frames_per_second &b)
-{
-    return !(a == b);
-}
-
 static bool frame_rate_property_needs_update(obs_property_t *p, const frame_rates_t &frame_rates)
 {
     auto fps_num = frame_rates.size();