cmake: put the Perl modules into the correct location again

In ccfba9e (Makefile: use "generate-perl.sh" to massage Perl
library, 2024-12-06), the previous strategy (which avoided spawning a
shell script to transform the files) was replaced by the same
`generate-perl.sh` invocation as for the Makefile-based build.

The only difference is that now the transformation tries to handle the
Perl modules in-place (which ends up in empty files because the same
file is used as input and output via stdin/stdout redirection), and the
Perl script cannot find them anymore because they are not in the
expected place.

Let's put them into the expected place again, i.e. into
`perl/build/lib/` instead of `perl/`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

contrib/buildsystems/CMakeLists.txt

@@ -882,6 +882,10 @@ foreach(script ${git_perl_scripts} ${perl_modules})
 	string(REPLACE ".perl" "" perl_gen_path "${script}")
 
 	get_filename_component(perl_gen_dir "${perl_gen_path}" DIRECTORY)
+	if(script MATCHES "\.pm$")
+		string(REGEX REPLACE "^perl" "perl/build/lib" perl_gen_dir "${perl_gen_dir}")
+		string(REGEX REPLACE "^perl" "perl/build/lib" perl_gen_path "${perl_gen_path}")
+	endif()
 	file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}/${perl_gen_dir}")
 
 	add_custom_command(OUTPUT "${CMAKE_BINARY_DIR}/${perl_gen_path}"