This patch enables the -Wstrict-calls-without-prototype warning by
default and fixes the existing clang test suite to pass.
This patch is considered work-in-progress because the patch it is
based on is not finalized. It is also unclear at this point whether this warning should actually
be enabled by default. So this patch serves to illustrate the changes
that would need to be made to have the warning on by default.
rdar://87118271