ARM: HFAs must be passed in consecutive registers

This is the clang counterpart to 208413, which ensures that Homogeneous
Floating-point Aggregates are passed in consecutive registers on ARM.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@208417 91177308-0d34-0410-b5e6-96231b3b80d8