package.py: use subprocess.Popen for rpmdeps call

package.py: use subprocess.Popen for rpmdeps call

* I've noticed errors like this in log.do_package:

  DEBUG: Executing python function package_do_filedeps
  sh: 1: Syntax error: "(" unexpected
  sh: 1: Syntax error: "(" unexpected
  DEBUG: Python function package_do_filedeps finished

  which are actually caused by some filenames included in package
  containing '()' characters

  Maybe we should change meta/classes/package.bbclass to
  fail when some filedeprunner call fails like this and fix
  filedeprunner to escape '()' and other possibly dangerous chars
  it's called like this:
  processed = list(pool.imap(oe.package.filedeprunner, pkglist))

* don't use shell=True
* show the command when it fails and let do_package task to fail

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>