Completely remove CFFI

No meaningful progress to update CFFI to experimental status
has been made since CFFI was disabled in SWIG-4.0.0 as the first
stage to removal. This commit is the final stage to remove it.

See issue #1966 for an attempt at updating CFFI to experimental
status. Anyone wishing for SWIG to support CFFI again might
want to utilise this work.

Examples/test-suite/cffi/Makefile.in

@@ -1,55 +0,0 @@
-#######################################################################
-# Makefile for cffi test-suite
-#######################################################################
-
-LANGUAGE     = cffi
-CFFI         = @CFFIBIN@
-SCRIPTSUFFIX = _runme.lisp
-
-HAVE_CXX11   = @HAVE_CXX11@
-HAVE_CXX14   = @HAVE_CXX14@
-HAVE_CXX17   = @HAVE_CXX17@
-HAVE_CXX20   = @HAVE_CXX20@
-srcdir       = @srcdir@
-top_srcdir   = @top_srcdir@
-top_builddir = @top_builddir@
-
-include $(srcdir)/../common.mk
-
-# Overridden variables here
-# no C++ tests for now
-CPP_TEST_CASES =
-#C_TEST_CASES +=
-
-# Custom tests - tests with additional commandline options
-# none!
-
-# Rules for the different types of tests
-%.cpptest:
-	$(setup)
-	+$(swig_and_compile_cpp)
-	$(run_testcase)
-
-%.ctest:
-	$(setup)
-	+$(swig_and_compile_c)
-	$(run_testcase)
-
-%.multicpptest:
-	$(setup)
-	+$(swig_and_compile_multi_cpp)
-	$(run_testcase)
-
-# Runs the testcase. A testcase is only run if
-# a file is found which has _runme.lisp appended after the testcase name.
-run_testcase = \
-	if [ -f $(SCRIPTDIR)/$(SCRIPTPREFIX)$*$(SCRIPTSUFFIX) ]; then \
-	  env LD_LIBRARY_PATH=.:$$LD_LIBRARY_PATH $(RUNTOOL) $(CFFI) -batch -s $(SCRIPTDIR)/$(SCRIPTPREFIX)$*$(SCRIPTSUFFIX); \
-	fi
-
-# Clean: (does nothing, we don't generate extra cffi code)
-%.clean:
-	@exit 0
-
-clean:
-	$(MAKE) -f $(top_builddir)/$(EXAMPLES)/Makefile SRCDIR='$(SRCDIR)' cffi_clean