Fix up SDL patch for latest SDL version

build.sh

@@ -538,9 +538,9 @@ build_sdl_mingw()
     prepare_sdl || failure
 
     echo "Patching SDL..." | tee -a $LOGFILE
-    cd $ROOT/3rdparty/sdl/src/video/wincommon || failure
+    cd $ROOT/3rdparty/sdl/src/video/windows || failure
     # patch: amend window class name (required by BOINC v6 screensaver!)
-    patch < $ROOT/patches/SDL_sysevents.c.patch >> $LOGFILE 2>&1 || failure
+    patch < $ROOT/patches/SDL_windowsevents.c.patch >> $LOGFILE 2>&1 || failure
     echo "Building SDL (this may take a while)..." | tee -a $LOGFILE
     cd $ROOT/3rdparty/sdl || failure
     chmod +x autogen.sh >> $LOGFILE 2>&1 || failure

patches/SDL_sysevents.c.patch

---- SDL_sysevents.c	2009-04-17 17:18:07.000000000 +0200
-+++ SDL_sysevents.c.new	2009-04-17 17:14:41.000000000 +0200
-@@ -799,7 +799,7 @@
- #define CS_BYTEALIGNCLIENT	0
- #endif
- 	if ( ! name && ! SDL_Appname ) {
--		name = "SDL_app";
-+		name = "BOINC_app";
- 		SDL_Appstyle = CS_BYTEALIGNCLIENT;
- 		SDL_Instance = hInst ? hInst : SDL_GetModuleHandle();
- 	}

patches/SDL_windowsevents.c.patch

+--- SDL_windowsevents.c	2020-03-05 10:46:34.201154000 +0000
++++ SDL_windowsevents.c	2020-03-05 10:54:16.394363000 +0000
+@@ -1211,7 +1211,7 @@
+         return (0);
+     }
+     if (!name && !SDL_Appname) {
+-        name = "SDL_app";
++        name = "BOINC_app";
+ #if defined(CS_BYTEALIGNCLIENT) || defined(CS_OWNDC)
+         SDL_Appstyle = (CS_BYTEALIGNCLIENT | CS_OWNDC);
+ #endif