angstrom-next: Use gold for linker eglibc based images for arm/x86

Remove unused pinnings, use linaro toolchains for arm
including gdb

use OE-Core toolchain for providing native and crossdk
components of toolchain. this helps to choose linaro or
OE-Core toolchain in a single tmpdir and per architecture
still being able to share common components. We really
dont care who provides native and crossdk components anyway
the arm code improvements that come from linaro gcc is
paramount for crossgcc and gcc on target and candian-gcc in
case of SDK where we will use it anyway

Update comments to match current state of affairs

beautify the files a bit

Signed-off-by: Khem Raj <raj.khem@gmail.com>