Switch building to Tools/Scripts/build-webkit.

Changes copied from Kubuntu packaging. Thanks!
New upstream build patch: upstream_changeset_119798.diff
Set --as-needed linker flag in rules.
Refresh patch: 02_add_nostrip_for_debug_packages.diff
Refresh patch: 03_hide_std_symbols.diff
Refresh patch: 04_enable_debug_information.diff
Refresh patch: 05_sparc_unaligned_access.diff
Remove patch: stabs_format_debug_info.diff

Flags are already set in debian/rules.
Refresh patch: no_gc_sections.diff
Refresh patch: defines_qt_webkit.diff
Refresh patch: glibc_hurd_mkspecs.diff
Refresh patch: hurd.diff
Update patch: webkit_qt_hide_symbols.diff
Refresh patch: ignore-unused-local-typedefs_error.diff
Update symbols.
Bump build dependencies for GStreamer.

gstreamer-0.10 is deprecated and unmaintained by upstream.
Add build-patch for gstreamer-1.0.
Add flex and bison build dependencies.
Add ruby build-dependency.
Add libfontconfig build dependency.