build-mingw-w64: Bump to the current version from March 23rd

This fixes the v*scanf functions when using msvcrt.dll, if using more
than 30 format conversions, fixes error handling in the btowc
function in libmingwex, and adds a missing (void) in a function
prototype in winpthreads, adds the fwpuclnt import library for aarch64,
plus other assorted header/interface updates.

build-mingw-w64.sh

@@ -18,7 +18,7 @@ set -e
 
 : ${DEFAULT_WIN32_WINNT:=0x601}
 : ${DEFAULT_MSVCRT:=ucrt}
-: ${MINGW_W64_VERSION:=9ed7b8dcfb3186fdfed1be2a374963458af618b1}
+: ${MINGW_W64_VERSION:=a3f6d363d534e9d5563a0b7c677889101e6bbd42}
 
 while [ $# -gt 0 ]; do
     case "$1" in