The flag "-coverage-function-names-in-data" is actually backwards -- we do

The flag "-coverage-function-names-in-data" is actually backwards -- we do
emit function names in .gcda files by default, and the flag turns that off!
Rename the flag to make it match what it actually does. This keeps the default
format compatible with gcc 4.2.

Also add a test for this flag.

llvm-svn: 177475