Please add missing C++20 Modules file extension

[yamader]

Is your feature request related to a problem? Please describe.

xmake does not recognize some file extensions used in C++ Modules.
Those extensions are supported by common compilers and should be supported by xmake as well.
Currently missing support is for .ccm, .cxxm, and .c++m.

cf. clang and gcc code
https://github.com/llvm/llvm-project/blob/dc410f94/clang/lib/Driver/Types.cpp#L364-L366
https://github.com/gcc-mirror/gcc/blob/ff41abd/gcc/cp/lang-specs.h#L43-L47

Describe the solution you'd like

Simply add the extensions (ccm・cxxm・c++m) here and it will work.

• https://github.com/xmake-io/xmake/blob/master/xmake/languages/c%2B%2B/xmake.lua#L23
• https://github.com/xmake-io/xmake/blob/master/xmake/rules/c%2B%2B/modules/xmake.lua#L25

Describe alternatives you've considered

No response

Additional context

No response

[waruqi]

you can open a pr to add them