x86: cleanups for toolchain

The 4.4.3 TC was still being specified in one spot.
Also, no need to cross-set x86/ARM variables when buliding
for ARM/x86.

Change-Id: Icbb0f772a983a24dc10ccab0800d4b7bbd60a099
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>