libdouble-conversion: move package here from packages-abandoned feed
It's a dependency for qt5base which got removed from the packages feed earlier due to no other package from the packages feed made us of it.
This also purges already back then (v5.9) legacy projects, such as Qt
Quick 1 / QML 1.
We also focus on software rendering only for now, postponing dealing
with messy vendor specific GL(ES) APIs, quirks and proprietary / binary
blobs. Implies certain features and packages being unavailable for the
moment.
Due to the switch from hotplug2 to procd, libudev - which libinput
requires - was rendered unusable on OpenWrt/LEDE.
However since there's libudev-fbsd now which is used as a
drop-in-replacement for libudev, we can now make use of libinput again
and therewith avoid the need of passing platform specific env vars
telling the paths to mouse/touchscreen/keyboard (evdev).
5.9 is a LTS tree so we're gonna stick to that version for a while now.
WARNING: This upgrade introduces a new dependency to pcre2 which is not
available in the lede-17.01 release branch!
Although Qt has the functionality of <host_build>'s,
it's supposed to be used and explicitly stated in
project files, so it can't be switched on from the
outside (e.g. via flags or env vars).
On top of that all builds using the <host_build>
directive get linked against libQtBootstrap.a which
is not always desired.
libQtBootstrap.a is also the only file available for
host builds, which means, <host_build>'s can't just make
use of and and link against e.g. libQtCore, as those
objects only get compiled for the target, not for the
host.
Because of above reasons, we build Qt twice now, once
for the host, once for the target.
When using the pkgconfig macros inside qmake
project files, qmake silently returns since it
detects being run inside a cross-toolchain and
pkgconfig normally doesn't work as expected in
such an environment.
However we patched pkgconfig to work inside
OpenWrt / LEDE (pkgconfig.real), so stop Qt
failing for qmake projects using pkgconfig.
Qt disables all pkg-config tests if it notices itself
being cross-compiled and PKG_CONFIG_SYSROOT_DIR being
unset.
However we do have a working pkg-config (wrapper around
pkg-config.real) which fixes the issues PKG_CONFIG_SYSROOT_DIR
tries to address.
Qt tries to be too smart in our case - force it to use
pkg-config.
Qt5-GUI now gets compiled with support for OpenGL,
however only links against GL stubs provided by the
2d software renderer.
That way we can decide at runtime, whether we want to
use GL or not - with almost no overhead, if not.
This also enables QtQuick2 being built correctly,
which depends on GL support and provides the
possibility of using QtQuick2 with the 2d-sw-renderer
even on hardware without native support for GL.
