GN: Fix Mac build for some tests.

tools/gn/secondary/third_party/mach_override/BUILD.gn

Index: tools/gn/secondary/third_party/mach_override/BUILD.gn
diff --git a/tools/gn/secondary/third_party/mach_override/BUILD.gn b/tools/gn/secondary/third_party/mach_override/BUILD.gn
index 1786c1d848f0f91875581831060058b6fe2977df..c17621889d94a13b12f97874e8180e821407f63f 100644
--- a/tools/gn/secondary/third_party/mach_override/BUILD.gn
+++ b/tools/gn/secondary/third_party/mach_override/BUILD.gn
@@ -2,10 +2,38 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+static_library("libudis86") {
+  external = true
+  sources = [
+    "libudis86/decode.c",
+    "libudis86/decode.h",
+    "libudis86/extern.h",
+    "libudis86/input.c",
+    "libudis86/input.h",
+    "libudis86/itab.c",
+    "libudis86/itab.h",
+    "libudis86/syn-att.c",
+    "libudis86/syn-intel.c",
+    "libudis86/syn.c",
+    "libudis86/syn.h",
+    "libudis86/types.h",
+    "libudis86/udint.h",
+    "libudis86/udis86.c",
+    "udis86.h",
+  ]
+  defines = [
+    "HAVE_ASSERT_H",
+    "HAVE_STRING_H",
+  ]
+}
+
 static_library("mach_override") {
   external = true
   sources = [
     "mach_override.c",
     "mach_override.h",
   ]
+  deps = [
+    ":libudis86",
+  ]
 }