binutils: another way to clear GPROFNG_ALTS for clang and musl

binutils: another way to clear GPROFNG_ALTS for clang and musl

It disables gprofng for toolchain clang and libc musl, so GPROFNG_ALTS
should be cleared for them. But override 'toolchain-clang' is applied
before overrides 'TRANSLATED_TARGET_ARCH' such as x86-64, then
GPROFNG_ALTS is still set and not cleared.

Apply overrides 'toolchain-clang' and 'libc-musl' for GPROFNGS rather
than GPROFNG_ALTS to make it work as expected.

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>