clutter: Remove no longer useful gitignore

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3500>

clutter/.gitignore

@@ -1,92 +0,0 @@
-ABOUT-NLS
-INSTALL
-Makefile
-Makefile.in
-aclocal.m4
-autom4te.cache
-compile
-*.pc
-.deps
-.libs
-*.o
-*.lo
-*.la
-*.gcov
-.dirstamp
-README
-stamp-enum-types
-stamp-marshal
-tags
-/ChangeLog*
-clutter-enum-types.[ch]
-clutter-marshal.[ch]
-gcov-report.txt
-clutter-json.h
-clutter-lcov.info
-clutter-lcov
-!/build/autotools/introspection.m4
-!/build/autotools/as-linguas.m4
-!/build/autotools/as-compiler-flag.m4
-!/build/autotools/glibtests.m4
-/build/autotools/*.m4
-/build/test-driver
-*.gir
-*.typelib
-*.gcda
-*.gcno
-config.*
-configure
-depcomp
-/doc/cookbook/*.pdf
-/doc/cookbook/html
-/doc/cookbook/*.stamp
-/doc/cookbook/clutter-cookbook.xml
-/doc/cookbook/clutter-cookbook.html
-doc/reference/clutter-*.txt
-!/doc/reference/clutter-sections.txt
-doc/reference/html
-doc/reference/tmpl
-doc/reference/xml
-doc/reference/clutter.args
-doc/reference/clutter.hierarchy
-doc/reference/clutter.interfaces
-doc/reference/clutter.prerequisites
-doc/reference/clutter.signals
-doc/reference/clutter-docs.xml
-doc/reference/*.stamp
-doc/reference/*.bak
-doc/reference/*.log
-doc/reference/gtkdoc-check.*
-gtk-doc.make
-install-sh
-libtool
-ltmain.sh
-missing
-mkinstalldirs
-stamp-h1
-TAGS
-/tests/tools/disable-npots.sh
-/tests/conform/test-launcher.sh
-/tests/interactive/wrapper.sh
-/po/POTFILES
-/po/clutter-1.0.pot
-/po/*.gmo
-/po/Makefile.in.in
-/po/Makevars.template
-/po/Rules-quot
-/po/boldquot.sed
-/po/en@boldquot.header
-/po/en@quot.header
-/po/insert-header.sin
-/po/quot.sed
-/po/remove-potcdate.sin
-/po/remove-potcdate.sed
-/po/stamp-po
-*.swn
-*.swo
-*.swp
-*~
-*.orig
-*.rej
-.DS_Store
-.testlogs-*