classes/update-alternatives: Skip alternatives when disabled
Skips the update alternative steps for recipes that shouldn't have them
enabled.
Fixes errors like:
nativesdk-bzip2-1.0.6-r5 do_package: bzip2: alternative target
(/opt/poky/2.5+snapshot/sysroots/i686-pokysdk-mingw32/usr/bin/bunzip2
or
/opt/poky/2.5+snapshot/sysroots/i686-pokysdk-mingw32/usr/bin/bunzip2.bzip2)
does not exist, skipping...
When building mingw SDKs
[YOCTO #12962]
Signed-off-by: Joshua Watt <JPEWhacker@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
