staging.bbclass: process installed dependencies in deterministic order as well

staging.bbclass: process installed dependencies in deterministic order as well

* similarly as direct dependencies before
* this doesn't fix any issue (at least AFAIK),
  just keeps the log files more deterministic to avoid unnecessary churn like in:

  perl-native.log.do_configure:
  -NOTE: Installed into sysroot: ['zlib-native', 'make-native', 'perlcross-native', 'gdbm-native', 'xz-native', 'gettext-minimal-native', 'texinfo-dummy-native', 'libtool-native']
  +NOTE: Installed into sysroot: ['zlib-native', 'make-native', 'perlcross-native', 'gdbm-native', 'libtool-native', 'gettext-minimal-native', 'texinfo-dummy-native', 'xz-native']

  and similarly in "Note: Skipping as already exists in sysroot:

Signed-off-by: Martin Jansa <martin.jansa@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>