x86, build, icc: Remove uninitialized_var() from compiler-intel.h

When compiling with icc, <linux/compiler-gcc.h> ends up included
because the icc environment defines __GNUC__.  Thus, we neither need
nor want to have this macro defined in both compiler-gcc.h and
compiler-intel.h, and the fact that they are inconsistent just makes
the compiler spew warnings.

Reported-by: Sunil K. Pandey <sunil.k.pandey@intel.com>
Cc: Kevin B. Smith <kevin.b.smith@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-0mbwou1zt7pafij09b897lg3@git.kernel.org
Cc: <stable@vger.kernel.org>