Why BUILDLINK_API_DEPEND.libdrm in libdrm/buildlink3.mk is so higher?

["OBATA Akio" <obache%netbsd.org@localhost>]

Hi,

Why BUILDLINK_API_DEPEND.libdrm in libdrm/buildlink3.mk is so higher (2.4.20)?
How may incompatibility were introduced since libdrm-2.4.0?

I've hit the issue on OpenBSD-5.0, builtin MesaLib(7.8.2) is allowed,
but libdrm(2.4.15) not, so failed to buildlink with MesaLib.

OK to reduce it to 2.4.0 (or 2.4.9 for graphics/MesaLib) ?
--
OBATA Akio / obache%NetBSD.org@localhost