tools: include sys/sysmacros.h on Linux

tools: include sys/sysmacros.h on Linux

Due to a bug in the glibc headers the macros makedev(), major() and
minor() where avaialble by including sys/types.h. This bug was
addressed in glibc-2.25 by introducing a warning when these macros are
used. Since Xen is build with -Werror this new warning cause a compile
error.

Use sys/sysmacros.h to define these three macros.

blktap2 is already Linux specific. The kernel header which was used to
get makedev() does not provided it anymore, and it was wrong to use a
kernel header anyway.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wei.liu2@citrix.com>