buildroot

yasm: New package

[thomas.petazzoni@free-electrons.com:

 drop the --disable-static from configuration options, the default
 behavior should work without problem.

 make sure the pre configure hook is also executed for the host
 variant of the package.

 add the project upstream URL in the package help text
]

Signed-off-by: Stefan Froberg <stefan.froberg@petroprogram.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>