sign_rpm: Allow pkg signing by chunks through RPM_GPG_SIGN_CHUNK
Commit
d58b1d196 moved from chunk to serial signing, but neither of both approaches
allowed the user to select the chunks size. This patch allows the user to select
a chunk size through RPM_GPG_SIGN_CHUNK defaulting to BB_NUMBER_THREADS, considered
a good default. Indirectly, this change reduces the number of processes spawn
to number-of-packages/RPM_GPG_SIGN_CHUNK.
Signed-off-by: Leonardo Sandoval <leonardo.sandoval.gonzalez@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
