build-gcc.sh: prevent generated binaries from containing hard-coded host build paths.

By copying the sysroot to the build directory, we prevent the generated binaries
to contain hard-coded host build paths (that eventually got searched for, which
resulted in really bad performance if the corresponding path corresponds to a
network-mounted partition).

Change-Id: I619ca00f0a7ccf57cf852424380a94009e4cdf15
3 files changed