zLib 1.2.12 fails to build in VC++/Win32 due to mismatched declarations

[gh-andre]

There are several errors in crc32.c, mostly due to mismatched argument size in a few calls. For example, crc32_combine_gen64 was seen first taking a 64-bit argument and then called here with a 32-bit one.

 uLong ZEXPORT crc32_combine_gen(len2)
     z_off_t len2;
 {
-    return crc32_combine_gen64(len2);
+    return crc32_combine_gen64((z_off64_t) len2);
 }

One more is due to crc32_combine_op being declared as an exported function in a header and then defined without the export declaration.

-uLong crc32_combine_op(crc1, crc2, op)
+uLong ZEXPORT crc32_combine_op(crc1, crc2, op)

You can see example failures here:

https://github.com/StoneStepsInc/zlib-nuget/runs/6747245701?check_suite_focus=true

Patches for these and Makefile.msc, which mixes up release/debug CRT, are available here.

https://github.com/StoneStepsInc/zlib-nuget/tree/master/patches