New 64-bit prebuilt linux toolchain to build SDK

This special 64-bit GCC 4.6 toolchain is used by linux sdk build to
ensure the generated host binaries can run on 64-bit Ubuntu 8.04 with
older Glibc and libstdc++.  It also comes with sysroot containing
libraries needed by sdk tools, such that compiling sdk tool becomes
less dependent on the pre-installed libraries at host.

At this moment it only generates 64-bit code for some sdk tools
(eg. emulator) and libraries lib64* they depend.  In the other
words, -m32 isn't accepted.  Please use its companion toolchain
i686-linux-glibc2.7-4.6 for 32-bit codegen.  Before this is built
with multilib, wrappers in /prebuilts/tools/gcc-sdk are used by Android
build system to select between i686-linux-glibc2.7-4.6 and
x86_64-linux-glibc2.7-4.6 based on the presence of -m32 and -m64 in
compiler options.

This is built by build-hardy-toolchain.sh (also enclosed, slightly
modified from digit@'s) with "--bootstrap" on 64-bit Ubuntu 8.04
(See http://b/issue?id=5957073).  It can run on 64-bit Ubuntu 8.04 too.

Change-Id: I6fe056d0da32ac27a2957c7493388c8fc9d7f336
2412 files changed