Inline small functions to greatly improve performance

Lots of small functions being defined in extra files meaningfully
increases runtime without link-time-optimization being enabled.
C11 supports marking functions as `inline` which sereves both as a hint
to the compiler as well as allowing definition inside the header.

imageprocess/image.c

@@ -2,11 +2,8 @@
 //
 // SPDX-License-Identifier: GPL-2.0-only
 
-#include <libavutil/frame.h>
-
-#include "imageprocess/blit.h"
 #include "imageprocess/image.h"
-#include "imageprocess/pixel.h"
+#include "imageprocess/blit.h"
 #include "lib/logging.h"
 #include "lib/math_util.h"
 
@@ -55,17 +52,6 @@ Image create_compatible_image(Image source, RectangleSize size, bool fill) {
                       source.abs_black_threshold);
 }
 
-RectangleSize size_of_image(Image image) {
-  return (RectangleSize){
-      .width = image.frame->width,
-      .height = image.frame->height,
-  };
-}
-
-Rectangle full_image(Image image) {
-  return rectangle_from_size(POINT_ORIGIN, size_of_image(image));
-}
-
 Rectangle clip_rectangle(Image image, Rectangle area) {
   Rectangle normal_area = normalize_rectangle(area);
 

imageprocess/image.h

@@ -4,9 +4,9 @@
 
 #pragma once
 
-#include "imageprocess/primitives.h"
+#include <libavutil/frame.h>
 
-typedef struct AVFrame AVFrame;
+#include "imageprocess/primitives.h"
 
 typedef struct {
   AVFrame *frame;
@@ -23,6 +23,15 @@ void replace_image(Image *image, Image *new_image);
 void free_image(Image *image);
 Image create_compatible_image(Image source, RectangleSize size, bool fill);
 
-RectangleSize size_of_image(Image image);
-Rectangle full_image(Image image);
+inline RectangleSize size_of_image(Image image) {
+  return (RectangleSize){
+      .width = image.frame->width,
+      .height = image.frame->height,
+  };
+}
+
+inline Rectangle full_image(Image image) {
+  return rectangle_from_size(POINT_ORIGIN, size_of_image(image));
+}
+
 Rectangle clip_rectangle(Image image, Rectangle area);