Rename (un)lock_mutex to mutex_(un)lock

For consistency, rename lock_mutex and unlock_mutex to mutex_lock and
mutex_unlock.

app/src/decoder.c

@@ -21,7 +21,7 @@ static int read_packet(void *opaque, uint8_t *buf, int buf_size) {
 // set the decoded frame as ready for rendering, and notify
 static void push_frame(struct decoder *decoder) {
     struct frames *frames = decoder->frames;
-    lock_mutex(frames->mutex);
+    mutex_lock(frames->mutex);
     if (!decoder->skip_frames) {
         while (!frames->rendering_frame_consumed) {
             SDL_CondWait(frames->rendering_frame_consumed_cond, frames->mutex);
@@ -32,7 +32,7 @@ static void push_frame(struct decoder *decoder) {
 
     frames_swap(frames);
     frames->rendering_frame_consumed = SDL_FALSE;
-    unlock_mutex(frames->mutex);
+    mutex_unlock(frames->mutex);
 
     static SDL_Event new_frame_event = {
         .type = EVENT_NEW_FRAME,

app/src/lockutil.h

@@ -1,14 +1,18 @@
 #ifndef LOCKUTIL_H
 #define LOCKUTIL_H
 
-static inline void lock_mutex(SDL_mutex *mutex) {
+#include <stdlib.h>
+#include <SDL2/SDL_log.h>
+#include <SDL2/SDL_mutex.h>
+
+static inline void mutex_lock(SDL_mutex *mutex) {
     if (SDL_LockMutex(mutex)) {
         SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "Could not lock mutex");
         exit(1);
     }
 }
 
-static inline void unlock_mutex(SDL_mutex *mutex) {
+static inline void mutex_unlock(SDL_mutex *mutex) {
     if (SDL_UnlockMutex(mutex)) {
         SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "Could not unlock mutex");
         exit(1);

app/src/screen.c

@@ -349,7 +349,7 @@ SDL_bool show_screen(const char *serial, Uint16 local_port) {
         case SDL_QUIT:
             goto screen_quit;
         case EVENT_NEW_FRAME:
-            lock_mutex(frames.mutex);
+            mutex_lock(frames.mutex);
             AVFrame *frame = frames.rendering_frame;
             frames.rendering_frame_consumed = SDL_TRUE;
             if (!decoder.skip_frames) {
@@ -364,7 +364,7 @@ SDL_bool show_screen(const char *serial, Uint16 local_port) {
             frame_size = current_frame_size;
 
             update_texture(frame, texture);
-            unlock_mutex(frames.mutex);
+            mutex_unlock(frames.mutex);
 
             texture_empty = SDL_FALSE;