release: Update MinGW-w64 toolchain

Author: dkl

contrib/release/build.sh

@@ -114,7 +114,7 @@ get_mingww64_toolchain() {
 
 	gccversion=4.9.2
 	dir=Toolchains%20targetting%20Win$bits/Personal%20Builds/mingw-builds/$gccversion/threads-win32/sjlj/
-	file=$arch-$gccversion-release-win32-sjlj-rt_v4-rev2.7z
+	file=$arch-$gccversion-release-win32-sjlj-rt_v4-rev3.7z
 
 	mkdir -p ../input/MinGW-w64
 	download "MinGW-w64/$file" "http://sourceforge.net/projects/mingw-w64/files/$dir$file/download"