magnum-integration: Fix build with modern Clang and enable aarch64 builds

mingw-w64-magnum-integration/PKGBUILD

@@ -7,10 +7,10 @@ pkgbase=mingw-w64-${_realname}
 pkgname="${MINGW_PACKAGE_PREFIX}-${_realname}"
 pkgver=2020.06
 _imgui_pkgver=1.76
-pkgrel=2
+pkgrel=4
 pkgdesc='Integration libraries for the Magnum C++11/C++14 graphics engine (mingw-w64)'
 arch=('any')
-mingw_arch=('mingw64' 'ucrt64' 'clang64')
+mingw_arch=('mingw64' 'ucrt64' 'clang64' 'clangarm64')
 url='https://magnum.graphics/'
 license=('MIT')
 depends=("${MINGW_PACKAGE_PREFIX}-magnum>=$pkgver"
@@ -48,6 +48,7 @@ build() {
     MSYS2_ARG_CONV_EXCL="-DCMAKE_INSTALL_PREFIX=" \
         ${MINGW_PREFIX}/bin/cmake \
             -G'Ninja' \
+            -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
             -DCMAKE_INSTALL_PREFIX=${MINGW_PREFIX} \
             -DWITH_BULLET=ON \
             -DWITH_DART=OFF \