build: Remove autotools

To avoid the burden of maintaining multiple build systems, this
patch removes autotools support.

https://bugzilla.gnome.org/show_bug.cgi?id=785414

man/Makefile.am

@@ -1,23 +0,0 @@
-XSLTPROC_FLAGS = \
-        --nonet \
-        --stringparam man.output.quietly 1 \
-        --stringparam funcsynopsis.style ansi \
-        --stringparam man.th.extra1.suppress 1 \
-        --stringparam man.authors.section.enabled 0 \
-        --stringparam man.copyright.section.enabled 0
-
-.xml.1:
-	$(AM_V_GEN) $(XSLTPROC) $(XSLTPROC_FLAGS) http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl $<
-
-man_MANS = \
-	gnome-control-center.1
-
-xml_files = $(man_MANS:.1=.xml)
-
-EXTRA_DIST = \
-	$(xml_files) \
-	meson.build
-
-DISTCLEANFILES = $(man_MANS)
-
--include $(top_srcdir)/git.mk