wasm-linker: update to llvm19 (add half-precision)

In llvm19 a new Wasm cpu-feature was added (half-precision). As linker
features have to match the cpu features in terms of integer value, the
new half-precision feature tag was added. The Wasm backend does not yet
make use of this new feature.

src/link/Wasm/types.zig

@@ -195,6 +195,7 @@ pub const Feature = struct {
         bulk_memory,
         exception_handling,
         extended_const,
+        half_precision,
         multimemory,
         multivalue,
         mutable_globals,
@@ -208,7 +209,7 @@ pub const Feature = struct {
 
         /// From a given cpu feature, returns its linker feature
         pub fn fromCpuFeature(feature: std.Target.wasm.Feature) Tag {
-            return @as(Tag, @enumFromInt(@intFromEnum(feature)));
+            return @enumFromInt(@intFromEnum(feature));
         }
 
         pub fn format(tag: Tag, comptime fmt: []const u8, opt: std.fmt.FormatOptions, writer: anytype) !void {
@@ -219,6 +220,7 @@ pub const Feature = struct {
                 .bulk_memory => "bulk-memory",
                 .exception_handling => "exception-handling",
                 .extended_const => "extended-const",
+                .half_precision => "half-precision",
                 .multimemory => "multimemory",
                 .multivalue => "multivalue",
                 .mutable_globals => "mutable-globals",
@@ -251,6 +253,7 @@ pub const known_features = std.StaticStringMap(Feature.Tag).initComptime(.{
     .{ "bulk-memory", .bulk_memory },
     .{ "exception-handling", .exception_handling },
     .{ "extended-const", .extended_const },
+    .{ "half-precision", .half_precision },
     .{ "multivalue", .multivalue },
     .{ "mutable-globals", .mutable_globals },
     .{ "nontrapping-fptoint", .nontrapping_fptoint },