Introduce common bzero libc implementation. (#23812)

* Introduce common `bzero` libc implementation.

* Update test name according to review

Co-authored-by: Linus Groh <mail@linusgroh.de>

* address code review

- import common implementation when musl or wasi is included
- don't use `c_builtins`, use `@memset`

* bzero calling conv to .c

* Apply review

Co-authored-by: Veikka Tuominen <git@vexu.eu>

---------

Co-authored-by: Linus Groh <mail@linusgroh.de>
Co-authored-by: Veikka Tuominen <git@vexu.eu>

lib/c.zig

@@ -17,6 +17,7 @@ comptime {
     if (builtin.target.isMuslLibC() or builtin.target.isWasiLibC()) {
         // Files specific to musl and wasi-libc.
         _ = @import("c/string.zig");
+        _ = @import("c/strings.zig");
     }
 
     if (builtin.target.isMuslLibC()) {

lib/c/strings.zig

@@ -0,0 +1,19 @@
+const std = @import("std");
+const common = @import("common.zig");
+
+comptime {
+    @export(&bzero, .{ .name = "bzero", .linkage = common.linkage, .visibility = common.visibility });
+}
+
+fn bzero(s: *anyopaque, n: usize) callconv(.c) void {
+    const s_cast: [*]u8 = @ptrCast(s);
+    @memset(s_cast[0..n], 0);
+}
+
+test bzero {
+    var array: [10]u8 = [_]u8{ '1', '2', '3', '4', '5', '6', '7', '8', '9', '0' };
+    var a = std.mem.zeroes([array.len]u8);
+    a[9] = '0';
+    bzero(&array[0], 9);
+    try std.testing.expect(std.mem.eql(u8, &array, &a));
+}

lib/libc/musl/src/string/bzero.c

@@ -1,8 +0,0 @@
-#define _BSD_SOURCE
-#include <string.h>
-#include <strings.h>
-
-void bzero(void *s, size_t n)
-{
-	memset(s, 0, n);
-}

src/musl.zig

@@ -1840,7 +1840,6 @@ const src_files = [_][]const u8{
     "musl/src/string/arm/__aeabi_memset.s",
     "musl/src/string/bcmp.c",
     "musl/src/string/bcopy.c",
-    "musl/src/string/bzero.c",
     "musl/src/string/explicit_bzero.c",
     "musl/src/string/i386/memset.s",
     "musl/src/string/index.c",

src/wasi_libc.zig

@@ -1044,7 +1044,6 @@ const libc_top_half_src_files = [_][]const u8{
     "musl/src/stdlib/qsort_nr.c",
     "musl/src/string/bcmp.c",
     "musl/src/string/bcopy.c",
-    "musl/src/string/bzero.c",
     "musl/src/string/explicit_bzero.c",
     "musl/src/string/index.c",
     "musl/src/string/memccpy.c",