It doesn't work with musl

[cmorve-te]

OpenOSC doesn't work with musl.

The main benefit I would see in OpenOSC is having a C-library-independent _FORTIFY_SOURCE. musl does indeed ask for such a library. But OpenOSC right now only works with glibc.

• It uses glibc-specific APIs
• It checks stuff against glibc-specific internal details (__sigset_t is not guaranteed to be defined by the standard), losing its main benefit.