Merge commit 64b31d96d from llvm git (by Nemanja Ivanovic):

[PowerPC] Do not attempt to reuse load for 64-bit FP_TO_UINT without
FPCVT

We call the function that attempts to reuse the conversion without
checking whether the target matches the constraints that the callee
expects. This patch adds the check prior to the call.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=43976

Differential revision: https://reviews.llvm.org/D77564

This should fix 'Assertion failed: ((Op.getOpcode() == ISD::FP_TO_SINT

FPCVT"), function LowerFP_TO_INTForReuse, file
/usr/src/contrib/llvm/lib/Target/PowerPC/PPCISelLowering.cpp, line 7276'
when building the devel/libslang2 port (and a few others) for PowerPC64.

Requested by: pkubaj
MFC after: 6 weeks
X-MFC-With: 358851