Enable warn_impcast_literal_float_to_integer by default.
This diagnostic seems to be production ready, it's just an oversight that it
wasn't turned on by default.
The test changes are a bit of a mixed bag. Some tests that seemed like they
clearly didn't need to use this behavior have been modified not to use it.
Others that I couldn't be sure about, I added the necessary expected-warnings
to.
It's possible the diagnostic message could be improved to make it clearer that
this warning can be suppressed by using a value that won't lose precision when
converted to the target type (but can still be a floating point literal, such
as "bool b = 1.0;").
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154068
91177308-0d34-0410-b5e6-
96231b3b80d8