[Process] Add validation on Process input
Merge branch '2.3' into 2.4

* 2.3:
  [WIP][Finder] Fix wrong implementation on sortable callback comparator
  ommited space
  [Validator] Fixed StaticMethodLoader on systems that don't have E_STRICT enabled by default
  Include file path in exception
  [Process] Add validation on Process input
Merge branch '2.4'

* 2.4:
  [WIP][Finder] Fix wrong implementation on sortable callback comparator
  ommited space
  [Validator] Fixed StaticMethodLoader on systems that don't have E_STRICT enabled by default
  Include file path in exception
  [Process] Add validation on Process input

Conflicts:
	src/Symfony/Component/Process/Process.php
	src/Symfony/Component/Process/ProcessBuilder.php
	src/Symfony/Component/Process/Tests/ProcessBuilderTest.php