Unreviewed build fix for the GTK port after r150305 and r150306.

* GNUmakefile.list.am:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150325 268f45cc-cd09-0410-ab3c-d52691b4dbfc
[GTK] Parallel build fails if gtk-doc is enabled
https://bugs.webkit.org/show_bug.cgi?id=116227

Patch by Alberto Garcia <agarcia@igalia.com> on 2013-05-18
Reviewed by Martin Robinson.

.:

* GNUmakefile.am:
Define an empty noinst_DATA variable where other automake files
can add additional objects to be built.

Source/WebCore:

* GNUmakefile.am:
Don't overwrite noinst_DATA, modify its existing value instead.

Tools:

* GNUmakefile.am:
Don't use the 'all' target to generate the documentation.
The prerequisites of this target must be files that need to be
built _before_ the actual compilation of WebKit starts. Since the
documentation depends on WebKit being built first, this means in
practice that the code will be built in parallel with the
generation of its dependencies, potentially making the build fail.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150326 268f45cc-cd09-0410-ab3c-d52691b4dbfc