Work on Mac GN build

tools/gn/secondary/third_party/nss/BUILD.gn

Index: tools/gn/secondary/third_party/nss/BUILD.gn
diff --git a/tools/gn/secondary/third_party/nss/BUILD.gn b/tools/gn/secondary/third_party/nss/BUILD.gn
index 278286d9983bd02bdfc8aa7f8c90c6706a32c757..926b180d21e981a04a0152bcc05858fa709374e0 100644
--- a/tools/gn/secondary/third_party/nss/BUILD.gn
+++ b/tools/gn/secondary/third_party/nss/BUILD.gn
@@ -213,11 +213,16 @@ if (is_linux) {
 
     configs -= [
       "//build/config/compiler:chromium_code",
-      "//build/config/win:unicode",  # Requires 8-bit mode.
-      "//build/config/win:lean_and_mean",  # Won"t compile with lean and mean.
     ]
+    if (is_win) {
+      configs -= [
+        "//build/config/win:unicode",  # Requires 8-bit mode.
+        "//build/config/win:lean_and_mean",  # Won"t compile with lean and mean.
+      ]
+    }
     configs += [ "//build/config/compiler:no_chromium_code" ]
 
+    cflags = []
     defines = [
       "_NSPR_BUILD",
       "FORCE_PR_LOG",
@@ -430,8 +435,13 @@ if (is_linux) {
 
     configs -= [
       "//build/config/compiler:chromium_code"
-      "//build/config/win:unicode",  # Requires 8-bit mode.
     ]
+
+    if (is_win) {
+      configs -= [
+        "//build/config/win:unicode",  # Requires 8-bit mode.
+      ]
+    }
     configs += [ "//build/config/compiler:no_chromium_code" ]
 
     include_dirs = [ "nss/lib/ckfw" ]
@@ -828,8 +838,12 @@ if (is_linux) {
 
     configs -= [
       "//build/config/compiler:chromium_code"
-      "//build/config/win:unicode",  # Requires 8-bit mode.
     ]
+    if (is_win) {
+      configs -= [
+        "//build/config/win:unicode",  # Requires 8-bit mode.
+      ]
+    }
     configs += [ "//build/config/compiler:no_chromium_code" ]
     direct_dependent_configs = [ ":nss_static_config" ]