zig build static library in windows should define SODIUM_STATIC

[sgwong]

I encounter linking error with zig build in windows when trying to buid another dynamic library which use sodium static library
lld-link: error: duplicate symbol: DllMain

It seems like when build static sodium library in windows it still include the DllMain. After reading the source code, I need to add the following line in the build.zig to resolve the issue.(line 89)
lib.defineCMacro("SODIUM_STATIC", "1");

[jedisct1]

That was fixed in d787d2b -- Thanks!