add target_abi to CrossTarget to use in build.zig

Author: vole-dev

lib/std/build.zig

@@ -2423,6 +2423,9 @@ pub const LibExeObjStep = struct {
         if (self.wasi_exec_model) |model| {
             try zig_args.append(builder.fmt("-mexec-model={s}", .{@tagName(model)}));
         }
+        if (self.target.target_abi) |target_abi| {
+            try zig_args.append(builder.fmt("-mabi={s}", .{target_abi.string()}));
+        }
 
         if (!self.target.isNative()) {
             try zig_args.append("-target");

lib/std/zig/cross_target.zig

@@ -37,6 +37,9 @@ pub const CrossTarget = struct {
     /// `null` means the native C ABI, if `os_tag` is native, otherwise it means the default C ABI.
     abi: ?Target.Abi = null,
 
+    /// `null` means the default processor specific target-abi.
+    target_abi: ?Target.TargetAbi = null,
+
     /// When `os_tag` is `null`, then `null` means native. Otherwise it means the standard path
     /// based on the `os_tag`.
     dynamic_linker: DynamicLinker = DynamicLinker{},