remove usage of deprecated standard library APIs (#2404)

No minimum Zig version bump is necessary because the changes are backwards compatible.

Author: mochalins

src/analyser/InternPool.zig

@@ -3813,7 +3813,7 @@ pub fn toInt(ip: *InternPool, val: Index, comptime T: type) ?T {
         },
         .int_u64_value => |int_value| std.math.cast(T, int_value.int),
         .int_i64_value => |int_value| std.math.cast(T, int_value.int),
-        .int_big_value => |int_value| int_value.getConst(ip).to(T) catch null,
+        .int_big_value => |int_value| int_value.getConst(ip).toInt(T) catch null,
         .null_value => 0,
         else => null,
     };

src/build_runner/shared.zig

@@ -18,7 +18,7 @@ pub const BuildConfig = struct {
         name: []const u8,
         path: []const u8,
     };
-    pub const AvailableOption = std.meta.FieldType(std.meta.FieldType(std.Build, .available_options_map).KV, .value);
+    pub const AvailableOption = @FieldType(@FieldType(std.Build, "available_options_map").KV, "value");
 };
 
 pub const Transport = struct {
@@ -145,7 +145,7 @@ pub const ServerToClient = struct {
 
 pub const BuildOnSaveSupport = union(enum) {
     supported,
-    invalid_linux_kernel_version: if (builtin.os.tag == .linux) std.meta.FieldType(std.posix.utsname, .release) else noreturn,
+    invalid_linux_kernel_version: if (builtin.os.tag == .linux) @FieldType(std.posix.utsname, "release") else noreturn,
     unsupported_linux_kernel_version: if (builtin.os.tag == .linux) std.SemanticVersion else noreturn,
     unsupported_zig_version: if (@TypeOf(os_support) == std.SemanticVersion) void else noreturn,
     unsupported_os: if (@TypeOf(os_support) == bool and !os_support) void else noreturn,

src/features/completions.zig

@@ -173,7 +173,7 @@ fn declToCompletion(builder: *Builder, decl_handle: Analyser.DeclWithHandle) err
         }
     }
 
-    const documentation: std.meta.FieldType(types.CompletionItem, .documentation) = .{
+    const documentation: @FieldType(types.CompletionItem, "documentation") = .{
         .MarkupContent = .{
             .kind = if (builder.server.client_capabilities.completion_doc_supports_md) .markdown else .plaintext,
             .value = try std.mem.join(builder.arena, "\n\n", doc_comments.constSlice()),