Check for the support for soft links with AC_PROG_LN_S

Signed-off-by: Davide Madrisan <davide.madrisan@gmail.com>
Check for the Linux types: size_t, ssize_t, and uid_t

Signed-off-by: Davide Madrisan <davide.madrisan@gmail.com>
configure - check for inline function support

Signed-off-by: Davide Madrisan <davide.madrisan@gmail.com>