Optional "lib" prefixes on build.zig

[lun-4]

The title is self-explanatory, but here's the real world use cases that led me to opening the issue:

• LÖVR's plugin loader does not account for lib prefixes by default, so I have to write require "libsomething" rather than require "something", even though the latter is the "practical default" across the lua ecosystem of native libraries.
• Counter-Strike 1.6 server plugins are also not using the lib prefix, requiring your configuration file to needlessly add it.
• PAM uses a different prefix entirely: pam_ (see /lib/security)

This can be done without a direct build.zig enhancement, as seen here, but I think we could add this as a configuration parameter since it's a common thing to do.

I don't know which would be the most ergonomic way to set a different prefix inside the build script, my suggestion is some setLibPrefix(prefix: []const u8). Here's an example:

    const lib = b.addSharedLibrary("rtsp", "src/main.zig", b.version(0, 0, 1));
    lib.setTarget(target);
    lib.setBuildMode(mode);
    lib.setLibPrefix("");
    lib.install();

Or, for a PAM library:

    const lib = b.addSharedLibrary("seven_factor_authentication", "src/main.zig", b.version(0, 0, 1));
    lib.setTarget(target);
    lib.setBuildMode(mode);
    lib.setLibPrefix("pam_");
    lib.install();

[daurnimator]

Duplicate of #2231 ?

[lun-4]

Oops, it is.