X86: fcmov doesn't handle all possible EFLAGS, fall back to a branch
for the others.
Otherwise it will try to use SSE patterns and fail horribly if sse is
disabled.
Fixes PR14035.
This should fix the following assertion failure:
Assertion failed: (Reg >= X86::FP0 && Reg <= X86::FP6 && "Expected FP
register!"), function getFPReg, file
contrib/llvm/lib/Target/X86/X86FloatingPoint.cpp, line 330.
which can show up when compiling contrib/compiler-rt, using -march=i686
through -march=pentium3 (CPU's which do support fcmov, but don't support
SSE2).
MFC after: 1 week
762496516b