Codechange: remove the unused lock around Blitter

src/gfx.cpp

@@ -1480,9 +1480,7 @@ void DrawDirtyBlocks()
 		if (!IsFirstModalProgressLoop()) CSleep(MODAL_PROGRESS_REDRAW_TIMEOUT);
 
 		/* Modal progress thread may need blitter access while we are waiting for it. */
-		VideoDriver::GetInstance()->ReleaseBlitterLock();
 		_modal_progress_paint_mutex.lock();
-		VideoDriver::GetInstance()->AcquireBlitterLock();
 		_modal_progress_work_mutex.lock();
 
 		/* When we ended with the modal progress, do not draw the blocks.

src/gfxinit.cpp

@@ -295,8 +295,6 @@ static bool SwitchNewGRFBlitter()
 	const bool animation_wanted = HasBit(_display_opt, DO_FULL_ANIMATION);
 	const char *cur_blitter = BlitterFactory::GetCurrentBlitter()->GetName();
 
-	VideoDriver::GetInstance()->AcquireBlitterLock();
-
 	for (uint i = 0; i < lengthof(replacement_blitters); i++) {
 		if (animation_wanted && (replacement_blitters[i].animation == 0)) continue;
 		if (!animation_wanted && (replacement_blitters[i].animation == 1)) continue;
@@ -306,7 +304,6 @@ static bool SwitchNewGRFBlitter()
 		const char *repl_blitter = replacement_blitters[i].name;
 
 		if (strcmp(repl_blitter, cur_blitter) == 0) {
-			VideoDriver::GetInstance()->ReleaseBlitterLock();
 			return false;
 		}
 		if (BlitterFactory::GetBlitterFactory(repl_blitter) == nullptr) continue;
@@ -323,8 +320,6 @@ static bool SwitchNewGRFBlitter()
 		if (BlitterFactory::SelectBlitter(cur_blitter) == nullptr || !VideoDriver::GetInstance()->AfterBlitterChange()) usererror("Failed to reinitialize video driver. Specify a fixed blitter in the config");
 	}
 
-	VideoDriver::GetInstance()->ReleaseBlitterLock();
-
 	return true;
 }
 

src/video/video_driver.hpp

@@ -62,7 +62,6 @@ public:
 
 	/**
 	 * Callback invoked after the blitter was changed.
-	 * This may only be called between AcquireBlitterLock and ReleaseBlitterLock.
 	 * @return True if no error.
 	 */
 	virtual bool AfterBlitterChange()
@@ -70,18 +69,6 @@ public:
 		return true;
 	}
 
-	/**
-	 * Acquire any lock(s) required to be held when changing blitters.
-	 * These lock(s) may not be acquired recursively.
-	 */
-	virtual void AcquireBlitterLock() { }
-
-	/**
-	 * Release any lock(s) required to be held when changing blitters.
-	 * These lock(s) may not be acquired recursively.
-	 */
-	virtual void ReleaseBlitterLock() { }
-
 	virtual bool ClaimMousePointer()
 	{
 		return true;