Revert "linux: Move {f}xstat{at} to compat symbols" for static build

Revert "linux: Move {f}xstat{at} to compat symbols" for static build

This reverts commit 20b39d59467b0c1d858e89ded8b0cebe55e22f60 for static
library.  This avoids the need to rebuild the world for the case where
libstdc++ (and potentially other libraries) are linked to a old glibc.

To avoid requering to provide xstat symbols for newer ABIs (such as
riscv32) a new LIB_COMPAT macro is added.  It is similar to SHLIB_COMPAT
but also works for static case (thus evaluating similar to SHLIB_COMPAT
for both shared and static case).

Checked with a check-abi on all affected ABIs. I also check if the
static library does contains the xstat symbols.