configure.ac: Update macros as suggested by 'autoconf --warnings=obsolete'.

git-svn-id: https://svn.code.sf.net/p/smartmontools/code/trunk/smartmontools@3933 4ea69e1a-61f1-4043-bf83-b5c94c648137
Makefile.am: Add creation of empty directories to install targets.

git-svn-id: https://svn.code.sf.net/p/smartmontools/code/trunk/smartmontools@3934 4ea69e1a-61f1-4043-bf83-b5c94c648137