Revert r137903, "Add experimental -Wstrlcpy-size warning that looks to see if...

Revert r137903, "Add experimental -Wstrlcpy-size warning that looks to see if the size argument for strlcpy/strlcat is the size of the *source*, and not the size of the *destination*.  This warning is off by default (for now)."

This currently doesn't work on Windows.

llvm-svn: 137920