fix typos

[QuarticCat]

Typos are spotted by typos program. Just want to reduce my vscode warnings.

BTW, I also want to fix some header file errors. For example, in mimalloc/prim.h, the code uses size_t and bool, but doesn't include <stddef.h> and <stdbool.h>. That won't cause compile errors since prim.c includes mimalloc.h before. However, IDEs (e.g. clangd) treats each header file as standalone. They won't know that C files will include other headers beforehand. Thus emitting a lot of errors. I want to add some includes to make IDEs happy. If you accept such a PR, I'll submit one soon.

[QuarticCat]

@microsoft-github-policy-service agree

[daanx]

Thanks!