[Process] Warn user with a useful message when tmpfile() failed
Merge branch '2.1' into 2.2

* 2.1:
  [FrameworkBundle] tweaked reference dumper command (see #7093)
  [HttpKernel] added some tests for previous merge
  Fix REMOTE_ADDR for cached subrequests
  [Process] Warn user with a useful message when tmpfile() failed

Conflicts:
	src/Symfony/Bundle/FrameworkBundle/Command/ConfigDumpReferenceCommand.php
[Process] Fix regression introduced in #6620 / 880da01c49a9255f5022ab7e18bca38c18f56370, fixes #7082
Merge branch '2.0' into 2.1

* 2.0:
  [Process] Fix regression introduced in #6620 / 880da01c49a9255f5022ab7e18bca38c18f56370, fixes #7082
Merge branch '2.1' into 2.2

* 2.1:
  [Process] Fix regression introduced in #6620 / 880da01c49a9255f5022ab7e18bca38c18f56370, fixes #7082