debian: Drop outdated stuff

The README.source is not usable anymore, and the Build-Conflicts
andd Breaks/Replaces are not needed anymore.

debian/README.source

@@ -1,6 +0,0 @@
-Build this package with:
-$ debian/rules arch-build
-or
-$ DEB_BUILD_PROG_OPTS="-S" debian/rules arch-build
-
-make sure you have the pre-build-depds in README.arch installed

debian/control

@@ -12,7 +12,6 @@ Build-Depends: dpkg-dev (>= 1.17.14), debhelper (>= 9.20160709~), libdb-dev,
  xsltproc, docbook-xsl, docbook-xml, po4a (>= 0.34-2),
  cmake (>= 3.4), pkg-config, libgtest-dev <!nocheck>, dh-systemd
 Build-Depends-Indep: doxygen, w3m, graphviz
-Build-Conflicts: autoconf2.13, automake1.4
 Vcs-Git: https://anonscm.debian.org/git/apt/apt.git
 Vcs-Browser: https://anonscm.debian.org/git/apt/apt.git
 Testsuite: autopkgtest
@@ -20,8 +19,6 @@ Testsuite: autopkgtest
 Package: apt
 Architecture: any
 Depends: ${shlibs:Depends}, ${misc:Depends}, ${apt:keyring}, gpgv | gpgv2 | gpgv1, adduser
-Replaces: manpages-pl (<< 20060617-3~), manpages-it (<< 2.80-4~), sun-java6-jdk (>> 0), sun-java5-jdk (>> 0), openjdk-6-jdk (<< 6b24-1.11-0ubuntu1~), bash-completion (<< 1:2.1-4.2+fakesync1), apt-utils (<< 1.3~exp2~)
-Breaks: manpages-pl (<< 20060617-3~), manpages-it (<< 2.80-4~), sun-java6-jdk (>> 0), sun-java5-jdk (>> 0), openjdk-6-jdk (<< 6b24-1.11-0ubuntu1~), apt-utils (<< 1.3~exp2~)
 Recommends: gnupg | gnupg2 | gnupg1
 Suggests: aptitude | synaptic | wajig, dpkg-dev (>= 1.17.2), apt-doc, python-apt, powermgmt-base
 Description: commandline package manager