[AArch64] only indicate CFI on Windows if we emitted CFI
Summary:
Otherwise, we emit directives for CFI without any actual CFI opcodes to
go with them, which causes tools to malfunction. The technique is
similar to what the x86 backend already does.
Fixes https://bugs.llvm.org/show_bug.cgi?id=40876
Patch by: froydnj (Nathan Froyd)
Reviewers: mstorsjo, eli.friedman, rnk, mgrang, ssijaric
Reviewed By: rnk
Subscribers: javed.absar, kristof.beyls, llvm-commits, dmajor
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61960
llvm-svn: 360816