I thought only having specific symlinks was enough, and it was for one
kernel. However, to make sure it works with all kernels, let's just add
symlinks for all the binutils.
* remove everything that causes conflicts when installing gcc6 and
gcc6-armhf side by side
* fix up the existing "if cross compiling" code path to use the
/usr/gcc6 prefix
* link binutils binaries to the locations they are expected to be
by gcc (this took me hours to figure out....) as well as by the
linux build system with CROSS_COMPILE
* link all gcc binaries to /usr/bin/gcc6-*
Based on the last version from Alpine, but installed to /usr/gcc6 and
with pretty much everything disabled except for the C compiler.
We can probably throw out a lot of patches, and make the APKBUILD much
smaller. But let's focus on making it possible to compile old kernels
again first. There's still a lot to do for that, see #103.
