community/nim: correct musl C imports and upgrade to 2.2.0

Musl defines SysThread * as a struct *pthread_t [1] rather than an unsigned long * as glibc does [2], and time_t as a 64-bit type for all architectures.

Correct the import definition to use a pointer type, time_t definition, and update to 2.2.0 (builds and tested with same patch)

[1] https://git.musl-libc.org/cgit/musl/tree/include/alltypes.h.in#n53 [2] https://sourceware.org/git?p=glibc.git;a=blob;f=sysdeps/nptl/bits/pthreadtypes.h;h=bace817f0b7e0873d66f3ee495e2cb1b92c6f32b;hb=HEAD#l27

Closes #16513 (closed)