Testament: build fails on 32-bit musl libc because d:nimUse64BitCTime isn't passed to compiler
### Description

Musl defines time_t as a 64 bit int on all platforms. When building against Musl (Alpine linux in this case) the build fails on 32-bit platforms because the `nimUse64BitCTime` flag isn't passed when building testament.

Example (from Alpine's CI - https://gitlab.alpinelinux.org/tokyovigilante/aports/-/jobs/1565125):

### Nim Version

2.2.0

### Current Output

```text
/home/buildozer/.cache/nim/testament_r/@m..@slib@spure@stimes.nim.c: In function 'getLocalOffsetAndDst__pureZtimes_u1906':
/home/buildozer/.cache/nim/testament_r/@m..@slib@spure@stimes.nim.c:2179:28: error: passing argument 1 of 'localtime' from incompatible pointer type [-Wincompatible-pointer-types]
 2179 |         tmPtr = localtime((&a));
      |                           ~^~~
      |                            |
      |                            long int *
In file included from /home/buildozer/.cache/nim/testament_r/@m..@slib@spure@stimes.nim.c:11:
/usr/include/time.h:60:23: note: expected 'const time_t *' {aka 'const long long int *'} but argument is of type 'long int *'
   60 | struct tm *localtime (const time_t *);
      |                       ^~~~~~~~~~~~~~
CC: ../lib/pure/concurrency/cpuinfo.nim
CC: ../lib/std/monotimes.nim
Error: execution of an external compiler program 'gcc -c  -w -fmax-errors=3 -pthread -O3 -fno-strict-aliasing -fno-ident -fno-math-errno   -I/builds/tokyovigilante/aports/community/nim/src/nim-2.2.0/lib -I/builds/tokyovigilante/aports/community/nim/src/nim-2.2.0/testament -o /home/buildozer/.cache/nim/testament_r/@m..@slib@spure@stimes.nim.c.o /home/buildozer/.cache/nim/testament_r/@m..@slib@spure@stimes.nim.c' failed with exit code: 1
FAILURE
```


### Expected Output

_No response_

### Known Workarounds

Force 64-bit time_t by patching `nim_posix_other.nim`.

### Additional Information

_No response_