Allow target commands to be invoked with no items (#14325).

Code such as

 target_include_directories(foo PRIVATE ${items})

should not work or break based on whether items is defined or not.
VS10: Honor user-specified /SUBSYSTEM: flag (#14326)

Use the WIN32_EXECUTABLE target property only to set the SubSystem build
attribute default.  When user-specified flags are later parsed they may
then override it.
Docs: Fix typo in CMAKE_DEBUG_TARGET_PROPERTIES

Introduced in commit f10e6480 (Docs: Document existing target
property debugging options., 2013-07-26)
FindGTK2: gthread-2.0 folder does not exist

Partially revert commit 508e8ca024e47baea342da85c7bbd014c7fd6c30
FindGTK2: Detect gmodule library
cmTarget: Add NAME property

In generator expression contexts, this can be used to determine the
name of the head target in the evaluation.
Export: Process generator expressions from INCLUDES DESTINATION.

Configuration sensitive expressions are not permitted.
Merge topic 'target-command-allow-no-items'

c0b8682 Allow target commands to be invoked with no items (#14325).
Merge topic 'vs-subsystem-order'

b64e8f2 VS10: Honor user-specified /SUBSYSTEM: flag (#14326)
Merge topic 'minor-cleanups'

7429941 Docs: Fix typo in CMAKE_DEBUG_TARGET_PROPERTIES
Merge topic 'FindGTK2-gmodule'

7ca5958 FindGTK2: Detect gmodule library
76c72b9 FindGTK2: gthread-2.0 folder does not exist
Merge topic 'INCLUDES-DESTINATION-no-config'

80e652f Export: Process generator expressions from INCLUDES DESTINATION.
4355815 cmTarget: Add NAME property