libstdc++.modules.json is new file in libstdc++ from GCC-15
it is the module mapping file used in C++ projects that
utilize C++20 modules
(From OE-Core rev: bbfe7ee5b64618649eb8aff753b444c97313e617)
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>