According to D53384, the default was switched from -fno-PIC to -fPIC to
work around a -fsanitize=leak bug on big-endian.
This gratuitous difference between little-endian and big-endian is
undesired, and not acceptable on powerpc64-unknown-freebsd. If
-fsanitize=leak still has the problem, we should default to -fPIC/-fPIE
only when -fsanitize=leak is specified.
powerpc64-ibm-aix is unaffected: it still defaults to -fPIC.
powerpc64-linux-musl is unaffected: it still defaults to -fPIE.