ant: add "build.xml" as a pattern

"build.xml" is the default input file name for ant.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
ant: add a pattern for picking a name of property as a tag

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Units, ant: use ant parser for build.xml.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>