[sanitizer] scanf: don't report stores that did not happen.

Respect REAL(scanf) return value and don't report memory stores that
could potentially happen, but did not.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@174887 91177308-0d34-0410-b5e6-96231b3b80d8
[sanitizer] clang-format pass over scanf code.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@174888 91177308-0d34-0410-b5e6-96231b3b80d8