Fixed for the difference of Cygwin with other Windows variants (MSVC,
Itanium, MinGW).
- The platform name is renamed to "cygwin" from "windows" which is used
for searching the standard libraries.
- The consideration for DLL storage class (DllExport/DllImport) is not
required for Cygwin and MinGW. There is no problem when linking in
these environment.
- Cygwin should use large memory model as default.(This may be changed
if someone ports to 32bit)
- Cygwin and MinGW should use the autolink feature in the sameway of
Linux due to the linker's limit.
We have no need for the other LLVM code generators (after all the main principle
of this smoke test is to only text X86 on macOS).
To implement this I had to split a couple of IRGen tests that involved multiple
code generator into multiple tests so I could use different REQUIRES lines. This
would be a nice feature to add to lit.
Use the target specific directive generation. This addresses a TODO to use the
same logic as clang. Unfortunately, the logic in clang is not accessible
outside of it, so replicate the behaviour.
COFF supports the `.drectve` section for embedding linker directives. LLVM has
long supported emitting this section. With this move, ELF shall become the only
target needing the autolink-extract functionality.
