Fail to build xapian-core/examples/xapian-pos.cc on android.
|Reported by:||mgautier||Owned by:||Olly Betts|
to_unsigned_int use errno but we don't include
On most compiler, the file is included by default but on android (at least),
it is not included and the file doesn't compile.
The patch (provided) is pretty simple, just include "errno.h".