The tests were not covering get for a symbol with a value. No symbol
has an uncommented value in the default config.h. (Actually there's
_CRT_SECURE_NO_DEPRECATE, but that's a bit of a hack that this script
is not expected to handle, so don't use it).
Add tests of "get FOO" after "set FOO" and "set FOO value", so that we
have coverage for "get FOO" when "FOO" has a value.