configure: modernize autoconf usage
configure: modernize autoconf usage

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 <0706025b2bbcec1ed8d64822f4eccd96314938d0@quendi.de>

Distrotech/flac,LordJZ/libflac,waitman/flac,waitman/flac,fredericgermain/flac,LordJZ/libflac,fredericgermain/flac,Distrotech/flac,fredericgermain/flac,waitman/flac,waitman/flac,fredericgermain/flac,LordJZ/libflac,Distrotech/flac,Distrotech/flac,waitman/flac,LordJZ/libflac