Remove polybar spec file

Polybar is now available as a native package in the major rpm-based
distros.

Ref: #1633

contrib/rpm/polybar.spec

@@ -1,71 +0,0 @@
-#
-# spec file for package polybar
-# Initially created for openSUSE
-#
-
-Name:           polybar
-Version:        3.4.1
-Release:        0
-Summary:        A fast and easy-to-use status bar
-License:        MIT
-Group:          System/GUI/Other
-URL:            https://github.com/polybar/polybar
-Source:         https://github.com/polybar/polybar/archive/%{version}.tar.gz
-BuildRequires:  clang >= 3.4
-BuildRequires:  cmake >= 3.1
-BuildRequires:  pkgconfig
-BuildRequires:  python-Sphinx
-BuildRequires:  python-xml
-BuildRequires:  xcb-util-image-devel
-BuildRequires:  xcb-util-wm-devel
-# optional dependency
-BuildRequires:  pkgconfig(alsa)
-# main dependency
-BuildRequires:  pkgconfig(cairo)
-BuildRequires:  pkgconfig(jsoncpp)
-BuildRequires:  pkgconfig(libcurl)
-BuildRequires:  pkgconfig(libpulse)
-BuildRequires:  pkgconfig(python3)
-BuildRequires:  pkgconfig(xcb)
-BuildRequires:  pkgconfig(xcb-proto)
-BuildRequires:  pkgconfig(xcb-util)
-%if 0%{?suse_version} <= 1315
-BuildRequires:  i3-devel
-%else
-BuildRequires:  i3-gaps-devel
-%endif
-%if 0%{?suse_version}
-BuildRequires:  libiw-devel
-%else
-BuildRequires:  wireless-tools-devel
-%endif
-
-%description
-A fast and easy-to-use status bar for tilling WM
-
-%prep
-%setup -q
-
-%build
-%cmake
-make
-
-%install
-%cmake_install
-
-%files
-%dir %{_datadir}/bash-completion/
-%dir %{_datadir}/bash-completion/completions
-%dir %{_datadir}/doc/%{name}
-%dir %{_datadir}/zsh/
-%dir %{_datadir}/zsh/site-functions
-%{_bindir}/%{name}
-%{_bindir}/%{name}-msg
-%{_datadir}/doc/%{name}/config
-%{_mandir}/man1/%{name}.1%{?ext_man}
-%{_datadir}/bash-completion/completions/%{name}
-%{_datadir}/zsh/site-functions/_%{name}
-%{_datadir}/zsh/site-functions/_%{name}_msg
-
-%changelog
-