upgrade musl to 1.2.5

[andrewrk]

musl 1.2.5 was released. It's time to follow the update procedure.

Release notes:

This release adds extension functions statx and preadv2/pwritev2, with fallback implementations for older kernels, and adds two new ports: loongarch64 and riscv32. Minor changes to the printf family of functions have been made for conformance to new standards interpretations/requirements. TLSDESC support for riscv64 has also been added.

Bugs fixed include some DNS issues related to new TCP fallback functionality, several rare race conditions, potentially incorrect return value when glob aborts, and several signifiant arch-specific bugs affecting TLSDESC on arm, riscv64 icache flushing, and sh sigsetjmp and dlsym RTLD_NEXT.