so that `nimony` won't be required for nightlies. It's annoying to build
`nimony` on each platform, e.g. `std/memfiles` which is used by `nimony`
is not supported by `nintendoswitch`
```
bin/nim compile -f --incremental:off --compileonly --gen_mapping --cc:gcc --skipUserCfg --os:nintendoswitch --cpu:arm64 -d:danger -d:gitHash:cd69f37f3a4fb46468b77b84ccf6aa3225c8895e compiler/nim.nim
```
```
/home/runner/work/nightlies/nightlies/nim/lib/pure/memfiles.nim(107, 40) Error: undeclared identifier: 'MAP_SHARED'
candidates (edit distance, scope distance); see '--spellSuggest':
(4, 5): 'freeShared'
```
(cherry picked from commit 46d4079357)
a5e73ff408