Migrate existing backends that care about software floating point
to use the information in the module rather than TargetOptions.

We've had and clang has used the use-soft-float attribute for some
time now so have the backends set a subtarget feature based on
a particular function now that subtargets are created based on
functions and function attributes.

For the one middle end soft float check go ahead and create
an overloadable TargetLowering::useSoftFloat function that
just checks the TargetSubtargetInfo in all cases.

Also remove the command line option that hard codes whether or
not soft-float is set by using the attribute for all of the
target specific test cases - for the generic just go ahead and
add the attribute in the one case that showed up.

llvm-svn: 237079
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index 6e0a6df..89aab26 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -145,6 +145,7 @@
   HasVMLxForwarding = false;
   SlowFPBrcc = false;
   InThumbMode = false;
+  UseSoftFloat = false;
   HasThumb2 = false;
   NoARM = false;
   IsR9Reserved = ReserveR9;