Convert GN single-item list concat to use lists.

tools/gn/secondary/third_party/zlib/BUILD.gn

Index: tools/gn/secondary/third_party/zlib/BUILD.gn
diff --git a/tools/gn/secondary/third_party/zlib/BUILD.gn b/tools/gn/secondary/third_party/zlib/BUILD.gn
index 7724822b82547d1e02f9f7ae2a6b367b62f5f28e..0e257f185e556545907b4198e08e5846ebfd2326 100644
--- a/tools/gn/secondary/third_party/zlib/BUILD.gn
+++ b/tools/gn/secondary/third_party/zlib/BUILD.gn
@@ -44,8 +44,8 @@ static_library("zlib") {
     "zutil.h",
   ]
 
-  configs -= "//build/config/compiler:chromium_code"
-  configs += "//build/config/compiler:no_chromium_code"
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
 
   direct_dependent_configs = [ ":zlib_config" ]
 }
@@ -81,8 +81,8 @@ static_library("minizip") {
 
   deps = [ ":zlib" ]
 
-  configs -= "//build/config/compiler:chromium_code"
-  configs += "//build/config/compiler:no_chromium_code"
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
   direct_dependent_configs = [ ":zlib_config" ]
 }