DAGCombine: prevent formation of illegal ConstantFP nodes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207850 91177308-0d34-0410-b5e6-96231b3b80d8
MC: place .file records into the correct section

.file records are supposed to have a section identifier of 65534
(IMAGE_SCN_DEBUG) rather than 0.  This is spelt out clearly within the PE/COFF
specification.  Fix this minor oversight with the implementation for support for
.file records.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207851 91177308-0d34-0410-b5e6-96231b3b80d8