powerpc: Reject binutils 2.24 when building little endian

commit 60e065f70bdb0b0e916389024922ad40f3270c96 upstream.

There is a bug in binutils 2.24 which causes miscompilation if we're
building little endian and using weak symbols (which the kernel does).

It is fixed in binutils commit 57fa7b8c7e59 "Correct elf_merge_st_other
arguments for weak symbols", which is in binutils 2.25 and has been
backported to the binutils 2.24 branch and has been picked up by most
distros it seems.

However if we're running stock 2.24 (no extra version) then the bug is
present, so check for that and bail.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Willy Tarreau <w@1wt.eu>