linuxPackages_*.perf: Fix build after kernel 4.1

In 4.1, the build system changed, and it now wants to execute ld like this:

ld -r -o util/scripting-engines/libperf-in.o util/scripting-engines/trace-event-perl.o util/scripting-engines/trace-event-python.o

The actual problem seems to be that `buildInputs = [elfutils ...]`
causes 'ld' to point to elfutils in PATH instead of the usual binutils.

So remove elfutils from buildInputs and set NIX_CFLAGS_* manually. This
is a slight hack, but there is some precedent:
https://github.com/NixOS/nixpkgs/blob/0761f81da71fc6a940c7f51129b6c7717db78e87/pkgs/tools/package-management/rpm/default.nix#L13

Fixes #9095.