not: Only consider exit code 3 to be a crash with --crash

This fixes Clang's test/Index/comment-xml-schema.c with Cygwin's
xmllint.exe, which uses exit(3) for XML validation failure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211550 91177308-0d34-0410-b5e6-96231b3b80d8
Support: Return scale from ScaledNumbers::matchScales()

This will be convenient when extracting `ScaledNumbers::getSum()`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211552 91177308-0d34-0410-b5e6-96231b3b80d8
Support: Extract ScaledNumbers::getSum() and getDifference()

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211553 91177308-0d34-0410-b5e6-96231b3b80d8
Fix comments from r211553

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211554 91177308-0d34-0410-b5e6-96231b3b80d8
BFI: Rename UnsignedFloat => ScaledNumber

A lot of the docs and API are out of date, but I'll leave that for a
separate commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211555 91177308-0d34-0410-b5e6-96231b3b80d8
BFI: Update ScaledNumber header docs

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211556 91177308-0d34-0410-b5e6-96231b3b80d8