libctf: get libctf-nobfd.ver from the right place with Solaris ld

We generate de-commented version scripts for Solaris ld (whose
-z gnu-version-script linker option does not support comments),
but after we switched to generating libctf-nobfd.ver itself, we
failed to adjust this code to pick it up from the new location.

libctf/
	PR libctf/33161
	* configure.ac: Fix libctf-nobfd.ver path on Solaris.
	* configure: Regenerated.