main/zmqpp: remove (!671)

The package was added with the initial Unity 8 packaging but even then
it seems that this package was never actually used.

Remove it because it no longer builds (some patches upstream might get
it building again).

[ci:skip-build]: already built successfully in CI

main/zmqpp/APKBUILD

-# Maintainer: Luca Weiss <luca@z3ntu.xyz>
-pkgname=zmqpp
-pkgver=4.2.0
-pkgrel=0
-pkgdesc="0mq 'highlevel' C++ bindings"
-url="http://zeromq.github.io/zmqpp"
-arch="x86_64"
-license="MPL2"
-depends=""
-makedepends="cmake zeromq-dev"
-install=""
-subpackages="$pkgname-dev"
-source="$pkgname-$pkgver.tar.gz::https://github.com/zeromq/zmqpp/archive/$pkgver.tar.gz"
-builddir="$srcdir/$pkgname-$pkgver"
-options="!check"
-
-prepare() {
-	default_prepare
-	mkdir "$builddir"/build
-}
-
-build() {
-	cd "$builddir"/build
-	cmake .. \
-		-DCMAKE_INSTALL_PREFIX=/usr \
-		-DCMAKE_BUILD_TYPE=Release
-	make
-}
-
-package() {
-	cd "$builddir"/build
-	make DESTDIR="$pkgdir/" install
-}
-
-sha512sums="a6b767278d85f38e5d78a958980782f15e3214db169ec2da118216c002657e525783d4ad3b9043d742801acf77b9b070ea12c18ec0e311e01f13d90d409277a7  zmqpp-4.2.0.tar.gz"