Move qfloat16-tables to util/ and commit its output

thiago said:

qfloat16-tables does not link to the bootstrap library (it's pure C++). The
only reason it's in C++ was so we didn't depend on Perl or Python during the
qtbase build on Windows (Perl is required on Unix). Also, its output is ALWAYS
the same and there is no input, since the constants are specified by IEEE 754.
I'd actually remove the tool from the build, move it to util/, and add the
resulting file to Git.