Undefined reference to `__libc_single_threaded`

### Comment:

Preface: I think this question is suited for this feedstock but feel free to re-direct me to another resource/area that is better suited.

Hi All,

I'm building a program that uses `pthreads` with a host that has GLIBC version of `2.37` but I'm encountering errors when building. Specifically I'm seeing an error that `__libc_single_threaded` is undefined.

Here is the program I'm compiling (simplified to just point to the `__libc_single_threaded` variable that is missing):

File: `a.c`
```
extern char __libc_single_threaded;

int main(void) {
return __libc_single_threaded;
}
```

Conda environment file: `temp-env.yaml`
```
channels:
- conda-forge
- nodefaults
dependencies:
- gcc
- gxx
- sysroot_linux-64
- conda-gcc-specs
- binutils
```

Cmdline (creates failure)
```
g++ a.c -o out
```

Error seen
```
<>/temp-env/bin/../lib/gcc/x86_64-conda-linux-gnu/13.2.0/../../../../x86_64-conda-linux-gnu/bin/ld: /tmp/ccGSVWOR.o: warning: relocation against `__libc_single_threaded' in read-only section `.text'
<>/temp-env/bin/../lib/gcc/x86_64-conda-linux-gnu/13.2.0/../../../../x86_64-conda-linux-gnu/bin/ld: /tmp/ccGSVWOR.o: in function `main':
a.c:(.text+0x7): undefined reference to `__libc_single_threaded'
<>/temp-env/bin/../lib/gcc/x86_64-conda-linux-gnu/13.2.0/../../../../x86_64-conda-linux-gnu/bin/ld: warning: creating DT_TEXTREL in a PIE
collect2: error: ld returned 1 exit status
```

Running a similar compile with the host compiler works. From my understanding this is because the isolated conda environment `libc` doesn't have the `__libc_single_threaded` variable defined while the host `libc` does? Is this an issue with the sysroot/environment that conda bundles together or do I need to somehow link against the `libc` of the host to get the variable?

Thanks in advance for any help or guidance!