libcpp: Regenerate aclocal.m4 and configure [PR 114748]

As discussed in the PR, aclocal.m4 and configure were incorrectly
regenerated at some point.

2024-04-17  Christophe Lyon  <christophe.lyon@linaro.org>

	PR preprocessor/114748
	libcpp/
	* aclocal.m4: Regenerate.
	* configure: Regenerate.