remove flutter/PKGBUILD, and modify build.py, not tested yet

flutter/PKGBUILD

@@ -1,33 +0,0 @@
-pkgname=rustdesk
-pkgver=1.2.0
-pkgrel=0
-epoch=
-pkgdesc=""
-arch=('x86_64')
-url=""
-license=('GPL-3.0')
-groups=()
-depends=('gtk3' 'xdotool' 'libxcb' 'libxfixes' 'alsa-lib' 'pulseaudio' 'ttf-arphic-uming' 'python-pip' 'curl' 'libappindicator-gtk3')
-makedepends=()
-checkdepends=()
-optdepends=()
-provides=()
-conflicts=()
-replaces=()
-backup=()
-options=()
-install=../pacman_install
-changelog=
-noextract=()
-md5sums=() #generate with 'makepkg -g'
-
-package() {
-	mkdir -p "${pkgdir}/usr/lib/rustdesk" && cp -r ${HBB}/build/linux/x64/release/bundle/* -t "${pkgdir}/usr/lib/rustdesk"
-	cp ${HBB}/build/linux/x64/release/liblibrustdesk.so  "${pkgdir}/usr/lib/rustdesk/librustdesk.so"
-  mkdir -p "${pkgdir}/usr/bin"
-  pushd ${pkgdir} && ln -s /usr/lib/rustdesk/flutter_hbb usr/bin/rustdesk && popd
-  install -Dm 644 $HBB/rustdesk.service -t "${pkgdir}/usr/share/rustdesk/files"
-  install -Dm 644 $HBB/rustdesk.desktop -t "${pkgdir}/usr/share/rustdesk/files"
-  # install -Dm 644 $HBB/../pynput_service.py -t "${pkgdir}/usr/share/rustdesk/files"
-  install -Dm 644 $HBB/../128x128@2x.png "${pkgdir}/usr/share/rustdesk/files/rustdesk.png"
-}