Switch apt source mirror and add upgrade note

packages/apt/build.sh

@@ -1,8 +1,11 @@
 TERMUX_PKG_HOMEPAGE=https://packages.debian.org/apt
 TERMUX_PKG_DESCRIPTION="Front-end for the dpkg package manager"
 TERMUX_PKG_DEPENDS="liblzma, libgnustl, dpkg, gnupg"
+# Wait with updating to later version until the NDK supports std::to_string() and other
+# functions (hopefully in r13):
 TERMUX_PKG_VERSION=1.2.12
-TERMUX_PKG_SRCURL=http://ftp.debian.org/debian/pool/main/a/apt/apt_${TERMUX_PKG_VERSION}.tar.xz
+# TERMUX_PKG_SRCURL=http://ftp.debian.org/debian/pool/main/a/apt/apt_${TERMUX_PKG_VERSION}.tar.xz
+TERMUX_PKG_SRCURL=https://launchpad.net/ubuntu/+archive/primary/+files/apt_${TERMUX_PKG_VERSION}.tar.xz
 TERMUX_PKG_EXTRA_CONFIGURE_ARGS="--host=${TERMUX_ARCH}-linux --disable-rpath acl_cv_rpath=$TERMUX_PREFIX/lib gt_cv_func_CFPreferencesCopyAppValue=no gt_cv_func_CFLocaleCopyCurrent=no ac_cv_c_bigendian=no --no-create"
 # When ready to drop bz2 support:
 TERMUX_PKG_EXTRA_CONFIGURE_ARGS+=" ac_cv_lib_bz2_BZ2_bzopen=no"