ChanTsune

Add `AT_EACCESS` to emscripten

1

Header source: [AT_EACCESS](https://github.com/emscripten-core/emscripten/blob/3073806d3fde4320c81cb2dc7cf0e00378f52df1/system/lib/libc/musl/include/fcntl.h#L68)

Add `getgrgid`, `getgrnam`, `getgrnam_r` and `getgrgid_r` for emscripten

1

I added `getgrgid`, `getgrnam`, `getgrnam_r` and `getgrgid_r` for emscripten. Header sources: [getgrgid](https://github.com/emscripten-core/emscripten/blob/3073806d3fde4320c81cb2dc7cf0e00378f52df1/system/lib/libc/musl/include/grp.h#L26) [getgrnam](https://github.com/emscripten-core/emscripten/blob/3073806d3fde4320c81cb2dc7cf0e00378f52df1/system/lib/libc/musl/include/grp.h#L27) [getgrgid_r](https://github.com/emscripten-core/emscripten/blob/127fb03dad7288a71f51bd46be49f1da8bdb0fa8/system/lib/libc/musl/include/grp.h#L29) [getgrnam_r](https://github.com/emscripten-core/emscripten/blob/127fb03dad7288a71f51bd46be49f1da8bdb0fa8/system/lib/libc/musl/include/grp.h#L30)

Add `getpwnam_r` and `getpwuid_r` to emscripten

1

`getpwnam` and `getpwuid` exist, but `*_r` functions do not exist for Emscripten, so I added them. Header sources: [getpwnam_r](https://github.com/emscripten-core/emscripten/blob/127fb03dad7288a71f51bd46be49f1da8bdb0fa8/system/lib/libc/musl/include/pwd.h#L39) [getpwuid_r](https://github.com/emscripten-core/emscripten/blob/127fb03dad7288a71f51bd46be49f1da8bdb0fa8/system/lib/libc/musl/include/pwd.h#L38)