Max Horn authored Dec 12, 2012 and Erik de Castro Lopo committed Dec 13, 2012

In particular:
- quote several macro arguments properly
- switch to the extended version of AC_INIT
- replace AM_CONFIG_HEADER by AC_CONFIG_HEADERS
- remove obsolete extra AC_CHECK_SIZEOF param
- upgrade minimal automake version from 1.7 to 1.11
  (which is when dist-xz was introduced)

Signed-off-by: Max Horn <max@quendi.de>