[GTK] Plugin process broken due to a missing symbol
https://bugs.webkit.org/show_bug.cgi?id=114901

Reviewed by Gustavo Noronha Silva.

Work around the missing symbols in the WebKitPluginProcess by specifying the required libraries
multiple times in the program's LDADD list. Libtool fights fiercely to avoid duplicate static library
references among the linker arguments (even if using the --preserve-dup-deps flag) so the required libraries
are specified in various ways.

The unresolved symbols in object files are no longer ignored as this can lead to further trouble (for instance
this patch also adds a few missing source files to the list of WebKitPluginProcess sources). The Freetype and
gamepad dependencies' libraries are also added to the binary's LDADD list.

* GNUmakefile.am:
* GNUmakefile.list.am: Add a few missing files to the build.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149169 268f45cc-cd09-0410-ab3c-d52691b4dbfc