stage2 LLVM: Correct long double for WASM

Also, f16 is not supported on this backend.

lib/std/target.zig

@@ -1789,6 +1789,8 @@ pub const Target = struct {
                 .powerpcle,
                 .powerpc64,
                 .powerpc64le,
+                .wasm32,
+                .wasm64,
                 => true,
 
                 else => false,

src/codegen/llvm.zig

@@ -10383,6 +10383,8 @@ fn backendSupportsF16(target: std.Target) bool {
         .powerpcle,
         .powerpc64,
         .powerpc64le,
+        .wasm32,
+        .wasm64,
         => false,
         else => true,
     };