libc: implement insque and remque in Zig

Implements insque() and remque() doubly-linked list functions
in lib/c/search.zig and removes musl C implementation.
Contributes to #30978

lib/c.zig

@@ -68,6 +68,7 @@ comptime {
         _ = @import("c/malloc.zig");
     }
     _ = @import("c/math.zig");
+    _ = @import("c/search.zig");
     _ = @import("c/stdlib.zig");
     _ = @import("c/string.zig");
     _ = @import("c/strings.zig");

lib/c/search.zig

@@ -0,0 +1,67 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const symbol = @import("../c.zig").symbol;
+
+comptime {
+    if (builtin.target.isMuslLibC() or builtin.target.isWasiLibC()) {
+        symbol(&insque, "insque");
+        symbol(&remque, "remque");
+    }
+}
+
+const Node = extern struct {
+    next: ?*Node,
+    prev: ?*Node,
+};
+
+fn insque(element: *anyopaque, pred: ?*anyopaque) callconv(.c) void {
+    const e: *Node = @ptrCast(@alignCast(element));
+
+    if (pred) |p_ptr| {
+        const p: *Node = @ptrCast(@alignCast(p_ptr));
+        e.next = p.next;
+        e.prev = p;
+        p.next = e;
+
+        if (e.next) |next| {
+            next.prev = e;
+        }
+    } else {
+        e.next = null;
+        e.prev = null;
+    }
+}
+
+fn remque(element: *anyopaque) callconv(.c) void {
+    const e: *Node = @ptrCast(@alignCast(element));
+
+    if (e.next) |next| next.prev = e.prev;
+    if (e.prev) |prev| prev.next = e.next;
+}
+
+test "insque and remque" {
+    var first = Node{ .next = null, .prev = null };
+    var second = Node{ .next = null, .prev = null };
+    var third = Node{ .next = null, .prev = null };
+
+    insque(&first, null);
+    try std.testing.expectEqual(@as(?*Node, null), first.next);
+    try std.testing.expectEqual(@as(?*Node, null), first.prev);
+
+    insque(&second, &first);
+    try std.testing.expectEqual(@as(?*Node, &second), first.next);
+    try std.testing.expectEqual(@as(?*Node, &first), second.prev);
+
+    insque(&third, &first);
+    try std.testing.expectEqual(@as(?*Node, &third), first.next);
+    try std.testing.expectEqual(@as(?*Node, &second), third.next);
+    try std.testing.expectEqual(@as(?*Node, &first), third.prev);
+    try std.testing.expectEqual(@as(?*Node, &third), second.prev);
+
+    remque(&third);
+    try std.testing.expectEqual(@as(?*Node, &second), first.next);
+    try std.testing.expectEqual(@as(?*Node, &first), second.prev);
+
+    remque(&second);
+    try std.testing.expectEqual(@as(?*Node, null), first.next);
+}

lib/libc/musl/src/search/insque.c

@@ -1,32 +0,0 @@
-#include <search.h>
-
-struct node {
-	struct node *next;
-	struct node *prev;
-};
-
-void insque(void *element, void *pred)
-{
-	struct node *e = element;
-	struct node *p = pred;
-
-	if (!p) {
-		e->next = e->prev = 0;
-		return;
-	}
-	e->next = p->next;
-	e->prev = p;
-	p->next = e;
-	if (e->next)
-		e->next->prev = e;
-}
-
-void remque(void *element)
-{
-	struct node *e = element;
-
-	if (e->next)
-		e->next->prev = e->prev;
-	if (e->prev)
-		e->prev->next = e->next;
-}

src/libs/musl.zig

@@ -1296,7 +1296,6 @@ const src_files = [_][]const u8{
     "musl/src/sched/sched_setscheduler.c",
     "musl/src/sched/sched_yield.c",
     "musl/src/search/hsearch.c",
-    "musl/src/search/insque.c",
     "musl/src/search/lsearch.c",
     "musl/src/search/tdelete.c",
     "musl/src/search/tdestroy.c",

src/libs/wasi_libc.zig

@@ -848,7 +848,6 @@ const libc_top_half_src_files = [_][]const u8{
     "musl/src/regex/fnmatch.c",
     "musl/src/regex/regerror.c",
     "musl/src/search/hsearch.c",
-    "musl/src/search/insque.c",
     "musl/src/search/lsearch.c",
     "musl/src/search/tdelete.c",
     "musl/src/search/tdestroy.c",