[GTK] Stop generating UserAgentGtk.h
https://bugs.webkit.org/show_bug.cgi?id=110582

Reviewed by Martin Robinson.

.: 

* configure.ac: Provide the USER_AGENT_GTK_(MAJOR|MINOR)_VERSION defines in the autotoolsconfig.h
header, containing the user agent versions that are to be used in the user agent string. The
WEBKIT_USER_AGENT_(MAJOR|MINOR)_VERSION name is avoided as the same defines are specified in the
webkitversion.h API header (but are not accessible from the WebCore layer). The UserAgentGtk.h
header is also not generated anymore from the input file.

Source/WebCore: 

No new tests - no new functionality.

* GNUmakefile.list.am: Move the UserAgentGtk.h build target from the derived sources list to
the list of the WebCore platform sources.
* platform/gtk/UserAgentGtk.cpp:
(WebCore::standardUserAgent): Rename WEBKIT_USER_AGENT_(MAJOR|MINOR)_VERSION to
USER_AGENT_GTK_(MAJOR|MINOR)_VERSION.
* platform/gtk/UserAgentGtk.h: Renamed from Source/WebCore/platform/gtk/UserAgentGtk.h.in.
Same as the input file expect for removed WEBKIT_USER_AGENT_(MAJOR|MINOR)_VERSION defines that
are now replaced by using the USER_AGENT_GTK_(MAJOR|MINOR)_VERSION defines placed in autotoolsconfig.h.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143875 268f45cc-cd09-0410-ab3c-d52691b4dbfc