Small POD fix

I don't know if it's valid POD or not to cram two POD tags together,
but it makes emacs unhappy.
Test for truth, not an integer.

False is not always 0, it could be '' or undef.  Truth is not always 1.
It is more robust to use ok() than is() to test for truth.
require, don't use.

Test::Compile tests that modules compile, it should not be running any
code.  This includes import routines.  It's not about testing pragmas.
And some modules have wacky import routines that might not work
without special setup or arguments.

This also avoids problems with things like pm_file_ok("path/to/Some/Module.pm")
which would try "use path::to::Some::Module" rather than "use Some::Module" and
try to call "path::to::Some::Module->import".

Also, it's more robust to check the return value of require than to
check for $@.
Add diagnostics on compilation failure.

Now you can know why it failed!  Makes heisenbugs so much easier to
track down.