std.Target: Remove special case for wasm in Abi.default().

It'll still pick .musl for os.tag == .wasi.

lib/std/Target.zig

@@ -815,7 +815,7 @@ pub const Abi = enum {
     // - vertex
 
     pub fn default(arch: Cpu.Arch, os: Os) Abi {
-        return if (arch.isWasm()) .musl else switch (os.tag) {
+        return switch (os.tag) {
             .freestanding, .other => switch (arch) {
                 // Soft float is usually a sane default for freestanding.
                 .arm,