toolchain/toolchain-buildroot: add comment about using virtual package infra
Commit "9a8ec9195c toolchain/toolchain-buildroot: migrate to virtual
package infrastructure" made the packages toolchain and
toolchain-buildroot to use the virtual package infra even they being
generic packages.
This works because on package/pkg-virtual.mk when a package do not
define neither _PROVIDES_ or _HAS_ symbols, only _IS_VIRTUAL is set to
YES and _VERSION and _SOURCE are set to empty before relaying the call
to inner-generic-package.
Add a comment explaining why the virtual package infra is used in these
cases.
Cc: Giulio Benetti <giulio.benetti@benettiengineering.com>
Cc: Romain Naour <romain.naour@gmail.com>
Cc: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit abcecd737b198e8a1a48bf4533e5c2b8de8b8cf4)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Ricardo Martincoski