system_win32: move win32_init here from easy.c

[jay]

.. since system_win32 is a more appropriate location for the functions
and to extern the globals.

Ref: ca597ad#r32446578
Reported-by: Gisle Vanem

Closes #xxxx

---

/cc @gvanem

[bagder]

The codacy red can be ignored.

[MarcelRaad]

I don't completely understand the Codacy failure - will it ever go away if this is merged as-is or will it stay red forever then?

The MinGW failures look legitimate, though:

system_win32.c: In function 'Curl_win32_init':
system_win32.c:85:23: error: implicit declaration of function 'Curl_sspi_global_init' [-Werror=implicit-function-declaration]
     CURLcode result = Curl_sspi_global_init();
                       ^~~~~~~~~~~~~~~~~~~~~
system_win32.c: In function 'Curl_win32_cleanup':
system_win32.c:106:3: error: implicit declaration of function 'Curl_sspi_global_cleanup' [-Werror=implicit-function-declaration]
   Curl_sspi_global_cleanup();
   ^~~~~~~~~~~~~~~~~~~~~~~~

[bagder]

will it ever go away if this is merged as-is or will it stay red forever then?

I think Codacy only makes red builds when it finds new issues. If you go there, you can see that it currently lists hundreds of existing issues. Most of them being benign and debatable, but some probably worthy to address.