hwdb: revert hwdb.bin back to /etc/udev

> Kay:
udev is early boot without /var. /var is entirely taboo for udev.

This partially reverts commit ee623f0d0c
(moving hwdb.bin is reverted, but the uninstall hook and cosmetic
changes remain).

Makefile.am

@@ -65,8 +65,7 @@ sysvinitdir=$(SYSTEM_SYSVINIT_PATH)
 varlogdir=$(localstatedir)/log
 systemdstatedir=$(localstatedir)/lib/systemd
 catalogstatedir=$(systemdstatedir)/catalog
-udevstatedir=$(localstatedir)/lib/udev
-hwdb_bin=$(udevstatedir)/hwdb.bin
+hwdb_bin=/etc/udev/hwdb.bin
 
 # Our own, non-special dirs
 pkgsysconfdir=$(sysconfdir)/systemd

man/udevadm.xml

@@ -424,13 +424,13 @@
     </refsect2>
 
     <refsect2><title>udevadm hwdb <optional>options</optional></title>
-      <para>Maintain the hardware database index in <filename>$(localstatedir)/lib/udev/hwdb.bin</filename>.</para>
+      <para>Maintain the hardware database index in <filename>/etc/udev/hwdb.bin</filename>.</para>
       <variablelist>
         <varlistentry>
           <term><option>--update</option></term>
           <listitem>
             <para>Compile the hardware dabase information located in /usr/lib/udev/hwdb.d/,
-            /etc/udev/hwdb.d/ and store it in <filename>$(localstatedir)/lib/udev/hwdb.bin</filename>. This should be done with
+            /etc/udev/hwdb.d/ and store it in <filename>/etc/udev/hwdb.bin</filename>. This should be done with
             any update to the source files, it will not be called automatically. The running
             udev daemon will detect a new database on its own and does not need to be
             notified about it.</para>