Since now the size of a c_longdouble is correctly 16 bytes,
the test is no longer passing. It was previously accidentally passing
due to incorrect sizing and it not being larger than the size
of a f64.
disable long_double test for windows
According to https://github.com/WebAssembly/tool-conventions/blob/main/BasicCABI.md
the size of c's long double is 16 bytes for Wasm, rather than 8 bytes
which was the value previously in the compiler. This ensures
we not only pass the correct value, but also creates the correct
function signature needed to pass the Wasm validator.
This also adds an additional test case in c_abi tests.
