[gn] port 1ae57fed880688 and fix mistake from 1203a24764bfa
diff --git a/llvm/utils/gn/secondary/libunwind/src/BUILD.gn b/llvm/utils/gn/secondary/libunwind/src/BUILD.gn
index f4aa67a..59f3981 100644
--- a/llvm/utils/gn/secondary/libunwind/src/BUILD.gn
+++ b/llvm/utils/gn/secondary/libunwind/src/BUILD.gn
@@ -38,7 +38,6 @@
   "UnwindLevel1.c",
   "UnwindRegistersRestore.S",
   "UnwindRegistersSave.S",
-  "Unwind_AIXExtras.cpp",
   "assembly.h",
   "cet_unwind.h",
   "config.h",
@@ -46,8 +45,8 @@
   "libunwind.cpp",
   "libunwind_ext.h",
 ]
-if (current_os == "mac") {
-  unwind_sources += [ "Unwind_AppleExtras.cpp" ]
+if (current_os == "aix") {
+  unwind_sources += [ "Unwind_AIXExtras.cpp" ]
 }
 
 if (current_os == "android") {