[GTK] Cleanup command-line defines

[GTK] Cleanup command-line defines
https://bugs.webkit.org/show_bug.cgi?id=109213

Reviewed by Xan Lopez.

.:

* GNUmakefile.am: Remove references to flags that are now provided
by autotoolsconfig.h
* configure.ac: Add new AC_DEFINE invocations for flags that were
before manually appended to the compiler CPPFLAGS and clump all
AC_DEFINE invocations together.

Source/WebCore:

* GNUmakefile.am: Remove references to flags that are now handled
via autotoolsconfig.h.

Source/WebKit/gtk:

* GNUmakefile.am: Remove references to flags that are now provided
by autotoolsconfig.h

Source/WebKit2:

* GNUmakefile.am:  Remove references to flags that are now
provided by autotoolsconfig.h.

Tools:

* TestWebKitAPI/config.h: Include the autotoolsconfig.h header to pick
up defines from autoconf.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@142179 268f45cc-cd09-0410-ab3c-d52691b4dbfc