Missing libm linkage for _core extension causes undefined symbol errors

[BwL1289]

Description

The msgspec._core extension module fails to load on some systems due to missing linkage against the math library (libm). This causes undefined symbol errors for mathematical functions like nextafter, fmod, and lround.

bash[./lib/python3.12/site-packages/msgspec/_core.cpython-312-aarch64-linux-gnu.so]:
    linux-vdso.so.1 (0x0000ffffbab2c000)
    libc.so.6 => /lib64/libc.so.6 (0x0000ffffba883000)
    /lib/ld-linux-aarch64.so.1 (0x0000ffffbaadf000)
undefined symbol: nextafter	(./lib/python3.12/site-packages/msgspec/_core.cpython-312-aarch64-linux-gnu.so)
undefined symbol: fmod	(./lib/python3.12/site-packages/msgspec/_core.cpython-312-aarch64-linux-gnu.so)
undefined symbol: lround	(./lib/python3.12/site-packages/msgspec/_core.cpython-312-aarch64-linux-gnu.so)

Workaround is to use a sed patch to explicitly link the math library:

sed -i 's/\(os\.path\.join([^)]*"_core\.c")\)\],/\1], libraries=["m"],/' "./setup.py""

Environment

Platform: aarch64-linux-gnu
Python version: 3.12
Architecture: ARM64