Don't use specific versions in autogen.sh

Not all distributions have the same version of aclocal, autoconf
or automake. Users can pass the name of a specific executables
via environment variables. Change configure.ac to require at
least autoconf 1.9.

Reviewed-by: iustinp

autogen.sh

@@ -10,8 +10,8 @@ set -e
 rm -rf config.cache autom4te.cache
 mkdir -p autotools
 
-aclocal-1.9 -I autotools
-autoconf
-automake-1.9 --add-missing -Wall -Wno-portability
+${ACLOCAL:-aclocal} -I autotools
+${AUTOCONF:-autoconf}
+${AUTOMAKE:-automake} --add-missing -Wall -Wno-portability
 
 rm -rf autom4te.cache

configure.ac

@@ -12,7 +12,7 @@ AC_PREREQ(2.59)
 AC_INIT(ganeti, gnt_version_full, ganeti@googlegroups.com)
 AC_CONFIG_AUX_DIR(autotools)
 AC_CONFIG_SRCDIR(configure)
-AM_INIT_AUTOMAKE([foreign tar-ustar])
+AM_INIT_AUTOMAKE([foreign tar-ustar 1.9])
 
 AC_SUBST([VERSION_MAJOR], gnt_version_major)
 AC_SUBST([VERSION_MINOR], gnt_version_minor)