libgcc: Disable multilib install for nativesdk

Fixes errors when building SDK for multilibbed enabled
architectures.

[YOCTO #3832]

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Constantin Musca <constantinx.musca@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
crosstap: handle hyphenated x86_64 target arch

systemtap_target_arch() should also translate x86-64 (hyphenated) into
x86_64 for the -a param.  Failing to do that causes systemtap to see
an architecture mismatch and create a cloned session with a bogusly
synthesized build directory path, and fails to compile the probe.

 Fixes [YOCTO #3756]

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>