Port member initialization from constructor to declaration (C++11)

Using `clang-tidy`'s `modernize-use-default-member-init` check and
manual review of the changes, and some extra manual changes that
`clang-tidy` failed to do.

Also went manually through all of `core` to find occurrences that
`clang-tidy` couldn't handle, especially all initializations done
in a constructor without using initializer lists.

2 files changed, 21 insertions, 38 deletions

diff --git a/modules/gdnative/videodecoder/video_stream_gdnative.cpp b/modules/gdnative/videodecoder/video_stream_gdnative.cpp
index f7d87595af..a2ff376e31 100644
--- a/modules/gdnative/videodecoder/video_stream_gdnative.cpp
+++ b/modules/gdnative/videodecoder/video_stream_gdnative.cpp
@@ -202,22 +202,7 @@ void VideoStreamPlaybackGDNative::update_texture() {
 // ctor and dtor
 
 VideoStreamPlaybackGDNative::VideoStreamPlaybackGDNative() :
-		texture(Ref<ImageTexture>(memnew(ImageTexture))),
-		playing(false),
-		paused(false),
-		mix_udata(nullptr),
-		mix_callback(nullptr),
-		num_channels(-1),
-		time(0),
-		seek_backward(false),
-		mix_rate(0),
-		delay_compensation(0),
-		pcm(nullptr),
-		pcm_write_idx(0),
-		samples_decoded(0),
-		file(nullptr),
-		interface(nullptr),
-		data_struct(nullptr) {}
+		texture(Ref<ImageTexture>(memnew(ImageTexture))) {}
 
 VideoStreamPlaybackGDNative::~VideoStreamPlaybackGDNative() {
 	cleanup();
diff --git a/modules/gdnative/videodecoder/video_stream_gdnative.h b/modules/gdnative/videodecoder/video_stream_gdnative.h
index 092e10a0f5..f1bae22801 100644
--- a/modules/gdnative/videodecoder/video_stream_gdnative.h
+++ b/modules/gdnative/videodecoder/video_stream_gdnative.h
@@ -37,13 +37,11 @@
 #include "scene/resources/video_stream.h"
 
 struct VideoDecoderGDNative {
-	const godot_videodecoder_interface_gdnative *interface;
-	String plugin_name;
+	const godot_videodecoder_interface_gdnative *interface = nullptr;
+	String plugin_name = "none";
 	Vector<String> supported_extensions;
 
-	VideoDecoderGDNative() :
-			interface(nullptr),
-			plugin_name("none") {}
+	VideoDecoderGDNative() {}
 
 	VideoDecoderGDNative(const godot_videodecoder_interface_gdnative *p_interface) :
 			interface(p_interface),
@@ -111,23 +109,23 @@ class VideoStreamPlaybackGDNative : public VideoStreamPlayback {
 	GDCLASS(VideoStreamPlaybackGDNative, VideoStreamPlayback);
 
 	Ref<ImageTexture> texture;
-	bool playing;
-	bool paused;
+	bool playing = false;
+	bool paused = false;
 
 	Vector2 texture_size;
 
-	void *mix_udata;
-	AudioMixCallback mix_callback;
+	void *mix_udata = nullptr;
+	AudioMixCallback mix_callback = nullptr;
 
-	int num_channels;
-	float time;
-	bool seek_backward;
-	int mix_rate;
-	double delay_compensation;
+	int num_channels = -1;
+	float time = 0;
+	bool seek_backward = false;
+	int mix_rate = 0;
+	double delay_compensation = 0;
 
-	float *pcm;
-	int pcm_write_idx;
-	int samples_decoded;
+	float *pcm = nullptr;
+	int pcm_write_idx = 0;
+	int samples_decoded = 0;
 
 	void cleanup();
 	void update_texture();
@@ -135,10 +133,10 @@ class VideoStreamPlaybackGDNative : public VideoStreamPlayback {
 protected:
 	String file_name;
 
-	FileAccess *file;
+	FileAccess *file = nullptr;
 
-	const godot_videodecoder_interface_gdnative *interface;
-	void *data_struct;
+	const godot_videodecoder_interface_gdnative *interface = nullptr;
+	void *data_struct = nullptr;
 
 public:
 	VideoStreamPlaybackGDNative();
@@ -181,7 +179,7 @@ class VideoStreamGDNative : public VideoStream {
 	GDCLASS(VideoStreamGDNative, VideoStream);
 
 	String file;
-	int audio_track;
+	int audio_track = 0;
 
 protected:
 	static void
@@ -194,7 +192,7 @@ public:
 	virtual void set_audio_track(int p_track);
 	virtual Ref<VideoStreamPlayback> instance_playback();
 
-	VideoStreamGDNative() { audio_track = 0; }
+	VideoStreamGDNative() {}
 };
 
 class ResourceFormatLoaderVideoStreamGDNative : public ResourceFormatLoader {