Python GDB intergration work for the build system.

Adds a --with-python=</path/to/python-config.sh> option.
Don't build GDB in canadian build->target

In canadian build->target is built first (eg. in order to build/run
executable on build system to generate table), then host->target.

Don't build GDB in build->target, because GDB doens't need it.  Besides,
--with-python= pointing to "host" header can fail "build"'s gcc.

Change-Id: Ic1a8a9d6fe5974a6747ca4342a336beea9987f47
Add x86_64 target configure defaults

It includes:
-march=atom/-mtune=atom to focus on Atom instructions/optimizations;
-fpmath=sse to generate sse math instructions instead of i387
-m32/-m64/-mx32 support to be able to generate 32/64/x32 code with
single toolchain.

Change-Id: I1a650b4cf572322baa5648a97e1731922571a132
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>
Replace -march=atom with -march=x86-64 for better host compatibility

Change-Id: Iefaa3ed65333c58484975326bfadd47ddaa92ce3
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>
Merge branch 'master' of https://android.googlesource.com/toolchain/build