Can't compile qtwebengine on ARM: safe_conversions_arm_impl.h not found

[2/172] CXX base/json/json_parser.o
FAILED: base/json/json_parser.o 
c++ -MMD -MF base/json/json_parser.o.d  -I/opt/qt5/qtwebengine/src/3rdparty/gn -I/opt/qt5/qtwebengine/src/3rdparty/gn/out/Release -DNDEBUG -O3 -fdata-sections -ffunction-sections -D_FILE_OFFSET_BITS=64 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -pthread -pipe -fno-exceptions -fno-rtti -std=c++14 -Wno-c++11-narrowing -c /opt/qt5/qtwebengine/src/3rdparty/gn/base/json/json_parser.cc -o base/json/json_parser.o
In file included from /opt/qt5/qtwebengine/src/3rdparty/gn/base/json/json_parser.cc:13:
/opt/qt5/qtwebengine/src/3rdparty/gn/base/numerics/safe_conversions.h:17:10: fatal error: base/numerics/safe_conversions_arm_impl.h: No such file or directory
 #include "base/numerics/safe_conversions_arm_impl.h"
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

$ docker run -v /usr/bin/qemu-arm-static:/usr/bin/qemu-arm-static --rm -ti arm32v7/gcc:latest

$ export QT_VERSION=5.12.0
$ export Qt5_DIR=/usr/local/Qt-$QT_VERSION
$ export LD_LIBRARY_PATH=/usr/local/lib:$Qt5_DIR/lib/
$ export PATH=$PATH:$Qt5_DIR/bin
$ apt-get update \
	&& apt-get upgrade -y \
	&& apt-get install -y \
		cmake \
		python-dev \
		libxml2-dev \
		libxslt-dev \
		libgtest-dev \
		libxcb-xinerama0-dev \
		libssl-dev \
		libxcursor-dev \
		libxcomposite-dev \
		libxdamage-dev \
		libxrandr-dev \
		libdbus-1-dev \
		libfontconfig1-dev \
		libcap-dev \
		libxtst-dev \
		libpulse-dev \
		libudev-dev \
		libpci-dev \
		libnss3-dev \
		libasound2-dev \
		libxss-dev \
		libgstreamer1.0-dev \
		libgstreamer-plugins-base1.0-dev \
		adwaita-icon-theme \
		autopoint \
		bsdmainutils \
		build-essential \
		dconf-gsettings-backend \
		dconf-service \
		debhelper \
		dh-autoreconf \
		dh-strip-nondeterminism \
		firebird-dev \
		firebird3.0-common \
		firebird3.0-common-doc \
		freetds-common \
		freetds-dev \
		gdb \
		gettext \
		gettext-base \
		gir1.2-atk-1.0 \
		gir1.2-atspi-2.0 \
		gir1.2-gst-plugins-base-1.0 \
		gir1.2-gstreamer-1.0 \
		gir1.2-gtk-3.0 \
		gir1.2-pango-1.0 \
		glib-networking \
		glib-networking-common \
		glib-networking-services \
		groff-base \
		gsettings-desktop-schemas \
		intltool-debian \
		iso-codes \
		libarchive-zip-perl \
		libasound2 \
		libasound2-data \
		libasyncns0 \
		libcupsimage2-dev \
		libdconf1 \
		libatk-bridge2.0-0 \
		libatk-bridge2.0-dev \
		libatk1.0-dev \
		libatspi2.0-0 \
		libatspi2.0-dev \
		libbabeltrace-ctf1 \
		libbabeltrace1 \
		libcap2-bin \
		libcolord2 \
		libct4 \
		libcups2-dev \
		libcupsimage2 \
		libdouble-conversion-dev \
		libdouble-conversion1 \
		libdrm-dev \
		libdrm2 \
		libdw1 \
		libegl1-mesa \
		libepoxy-dev \
		libepoxy0 \
		libevdev2 \
		libfbclient2 \
		libfile-stripnondeterminism-perl \
		libflac8 \
		libgbm-dev \
		libgbm1 \
		libgl1-mesa-dev \
		libgl1-mesa-glx \
		libglapi-mesa \
		libgles2-mesa \
		libgles2-mesa-dev \
		libglu1-mesa \
		libglu1-mesa-dev \
		libgraphite2-dev \
		libgstreamer-plugins-base1.0-0 \
		libgstreamer1.0-0 \
		libgtk-3-0 \
		libgtk-3-common \
		libgtk-3-dev \
		libgudev-1.0-0 \
		libib-util \
		libinput-bin \
		libinput-dev \
		libinput10 \
		libjson-glib-1.0-0 \
		libjson-glib-1.0-common \
		libmtdev-dev \
		libmtdev1 \
		libodbc1 \
		libogg0 \
		liborc-0.4-0 \
		libpango1.0-dev \
		libpangoxft-1.0-0 \
		libpciaccess0 \
		libpipeline1 \
		libpopt0 \
		libproxy-dev \
		libproxy1v5 \
		libpulse-mainloop-glib0 \
		libpulse0 \
		libpython3.5 \
		librest-0.7-0 \
		libsndfile1 \
		libsoup-gnome2.4-1 \
		libsoup2.4-1 \
		libsybdb5 \
		libtimedate-perl \
		libtommath1 \
		libvorbis0a \
		libvorbisenc2 \
		libwacom-common \
		libwacom2 \
		libwayland-bin \
		libwayland-client0 \
		libwayland-cursor0 \
		libwayland-dev \
		libwayland-egl1-mesa \
		libwayland-server0 \
		libwrap0 \
		libx11-xcb-dev \
		libx11-xcb1 \
		libxcb-dri2-0 \
		libxcb-dri2-0-dev \
		libxcb-dri3-0 \
		libxcb-dri3-dev \
		libxcb-glx0 \
		libxcb-glx0-dev \
		libxcb-icccm4 \
		libxcb-icccm4-dev \
		libxcb-image0 \
		libxcb-image0-dev \
		libxcb-keysyms1 \
		libxcb-keysyms1-dev \
		libxcb-present-dev \
		libxcb-present0 \
		libxcb-randr0 \
		libxcb-randr0-dev \
		libxcb-render-util0 \
		libxcb-render-util0-dev \
		libxcb-shape0 \
		libxcb-shape0-dev \
		libxcb-sync-dev \
		libxcb-sync1 \
		libxcb-util0 \
		libxcb-xfixes0 \
		libxcb-xfixes0-dev \
		libxcb-xinerama0 \
		libxcb-xkb-dev \
		libxcb-xkb1 \
		libegl1-mesa-dev \
		gperf \
		bison \
		libxfixes-dev \
		libxft-dev \
		libxft2 \
		libxi-dev \
		libxinerama-dev \
		libxkbcommon-dev \
		libxkbcommon-x11-0 \
		libxkbcommon-x11-dev \
		libxkbcommon0 \
		libxshmfence-dev \
		libxshmfence1 \
		libxtst6 \
		libxxf86vm-dev \
		libxxf86vm1 \
		man-db \
		mesa-common-dev \
		odbcinst \
		odbcinst1debian2 \
		pkg-kde-tools \
		po-debconf \
		publicsuffix \
		unixodbc-dev \
		wayland-protocols \
		x11proto-composite-dev \
		x11proto-damage-dev \
		x11proto-dri2-dev \
		x11proto-fixes-dev \
		x11proto-gl-dev \
		x11proto-randr-dev \
		x11proto-record-dev \
		x11proto-xf86vidmode-dev \
		x11proto-xinerama-dev \
		xkb-data \
		libpcre2-dev \
		flex \
	&& apt-get clean \
	&& cd /opt \
	&& git clone https://code.qt.io/qt/qt5.git \
	&& cd qt5 \
	&& git checkout origin/$QT_VERSION \
	&& perl init-repository \
	&& ./configure -opensource -nomake examples -nomake tests \
            -confirm-license \
	&& make -j8