MFV: Only emit movw on ARMv6T2

Building for the FreeBSD default target ARMv6 was emitting movw ASM on certain
test cases (found building qmake4/5 for ARM). Don't do that, moreover, the AS
in base doesn't understand this instruction for this target. One would need
to use --integrated-as to get this to build if desired.

http://llvm.org/viewvc/llvm-project?view=revision&revision=216989

Submitted by: ian
Reviewed by: dim
Obtained from: llvm.org
MFC after: 2 days