WIN32: Linking with the CRT at runtime. (#570)

Disclaimer: Forgive me if my format sucks, I've never submitted a PR before!

Fixes: #517 

I added a few things to allow zig to link with the CRT properly both statically and dynamically. In Visual Studio 2017, Microsoft changed how the c-runtime is factored again. With this change, they also added a COM interface to allow you to query the respective Visual Studio instance for two of them. This does that and also falls back on a registry query for 2015 support. If you're using a Visual Studio instance older than 2015, you'll have to use the existing options available with the zig compiler. Changes are listed below along with a general description of the changes.

all_types.cpp:

The separate variables for msvc/kern32 have been removed and all win32 libc directory paths have been combined into a ZigList since we're querying more than two directories and differentiating one from another doesn't matter to lld.

analyze.cpp:

The existing functions were extended to support querying libc libs & libc headers at runtime.

codegen.cpp/hpp:

Microsoft uses the new 'Universal C Runtime' name now. Doesn't matter from a functionality standpoint. I left the compiler switches as is to not introduce any breaking changes.

link.cpp:

We're linking 4 libs and generating another in order to support the UCRT.
Dynamic: msvcrt/d, vcruntime/d, ucrt/d, legacy_stdio_definitions.lib
Static: libcmt/d, libvcruntime/d libucrt/d, legacy_stdio_definitions.lib

main.cpp:

Update function call names.

os.cpp/hpp:

COM/Registry interface for querying Windows UCRT/SDK.

Sources:
[Windows CRT](https://docs.microsoft.com/en-us/cpp/c-runtime-library/crt-library-features)
[VS 2015 Breaking Changes](https://msdn.microsoft.com/en-us/library/bb531344.aspx)

1 files changed, 1 insertions, 1 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 358f1cf255..b3622a4e43 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -758,7 +758,7 @@ int main(int argc, char **argv) {
             if (libc_include_dir)
                 codegen_set_libc_include_dir(g, buf_create_from_str(libc_include_dir));
             if (msvc_lib_dir)
-                codegen_set_msvc_lib_dir(g, buf_create_from_str(msvc_lib_dir));
+                codegen_set_ucrt_lib_dir(g, buf_create_from_str(msvc_lib_dir));
             if (kernel32_lib_dir)
                 codegen_set_kernel32_lib_dir(g, buf_create_from_str(kernel32_lib_dir));
             if (dynamic_linker)