std.Target: Move osArchName() and Cpu.Arch.archName() to std.zig.target.

These deal with how Zig stores OS headers in `lib/libc/include` and so don't
really belong in std.Target.

lib/std/Target.zig

@@ -218,23 +218,6 @@ pub const Os = struct {
                 .windows => .windows,
             };
         }
-
-        pub fn archName(tag: Tag, arch: Cpu.Arch) [:0]const u8 {
-            return switch (tag) {
-                .linux => switch (arch) {
-                    .arm, .armeb, .thumb, .thumbeb => "arm",
-                    .aarch64, .aarch64_be => "aarch64",
-                    .loongarch32, .loongarch64 => "loongarch",
-                    .mips, .mipsel, .mips64, .mips64el => "mips",
-                    .powerpc, .powerpcle, .powerpc64, .powerpc64le => "powerpc",
-                    .riscv32, .riscv64 => "riscv",
-                    .sparc, .sparc64 => "sparc",
-                    .x86, .x86_64 => "x86",
-                    else => @tagName(arch),
-                },
-                else => @tagName(arch),
-            };
-        }
     };
 
     /// Based on NTDDI version constants from
@@ -3357,10 +3340,6 @@ pub fn cCallingConvention(target: Target) ?std.builtin.CallingConvention {
     };
 }
 
-pub fn osArchName(target: std.Target) [:0]const u8 {
-    return target.os.tag.archName(target.cpu.arch);
-}
-
 const Target = @This();
 const std = @import("std.zig");
 const builtin = @import("builtin");

lib/std/zig/LibCDirs.zig

@@ -187,7 +187,7 @@ pub fn detectFromBuilding(
         "{s}" ++ s ++ "libc" ++ s ++ "include" ++ s ++ "generic-{s}",
         .{ zig_lib_dir, generic_name },
     );
-    const generic_arch_name = target.osArchName();
+    const generic_arch_name = std.zig.target.osArchName(target);
     const arch_os_include_dir = try std.fmt.allocPrint(
         arena,
         "{s}" ++ s ++ "libc" ++ s ++ "include" ++ s ++ "{s}-{s}-any",

lib/std/zig/target.zig

@@ -129,6 +129,23 @@ pub fn glibcRuntimeTriple(
     };
 }
 
+pub fn osArchName(target: std.Target) [:0]const u8 {
+    return switch (target.os.tag) {
+        .linux => switch (target.cpu.arch) {
+            .arm, .armeb, .thumb, .thumbeb => "arm",
+            .aarch64, .aarch64_be => "aarch64",
+            .loongarch32, .loongarch64 => "loongarch",
+            .mips, .mipsel, .mips64, .mips64el => "mips",
+            .powerpc, .powerpcle, .powerpc64, .powerpc64le => "powerpc",
+            .riscv32, .riscv64 => "riscv",
+            .sparc, .sparc64 => "sparc",
+            .x86, .x86_64 => "x86",
+            else => @tagName(target.cpu.arch),
+        },
+        else => @tagName(target.cpu.arch),
+    };
+}
+
 pub fn muslArchName(arch: std.Target.Cpu.Arch, abi: std.Target.Abi) [:0]const u8 {
     return switch (abi) {
         .muslabin32 => "mipsn32",

src/glibc.zig

@@ -469,7 +469,7 @@ fn add_include_dirs(comp: *Compilation, arena: Allocator, args: *std.ArrayList([
     try args.append("-I");
     try args.append(try lib_path(comp, arena, lib_libc ++ "include" ++ s ++ "generic-glibc"));
 
-    const arch_name = target.osArchName();
+    const arch_name = std.zig.target.osArchName(target);
     try args.append("-I");
     try args.append(try std.fmt.allocPrint(arena, "{s}" ++ s ++ "libc" ++ s ++ "include" ++ s ++ "{s}-linux-any", .{
         comp.zig_lib_directory.path.?, arch_name,