Add is_official_build=true to common base bundle

Issue #388 revealed that linux_rooted can handle this with a patch,
which means all configurations *should* support this.

See #390

resources/config_bundles/archlinux/gn_flags.map

@@ -1,3 +1,2 @@
 custom_toolchain="//build/toolchain/linux/unbundle:default"
 host_toolchain="//build/toolchain/linux/unbundle:default"
-is_official_build=true

resources/config_bundles/common/gn_flags.map

@@ -22,6 +22,7 @@ google_api_key=""
 google_default_client_id=""
 google_default_client_secret=""
 is_debug=false
+is_official_build=true
 optimize_webui=false
 proprietary_codecs=true
 remove_webcore_debug_symbols=true

resources/config_bundles/windows/gn_flags.map

@@ -2,8 +2,7 @@ chrome_pgo_phase=0
 clang_use_chrome_plugins=false
 full_wpo_on_official=false
 is_clang=true
-is_official_build=true
 rtc_use_lto=false
 target_cpu="x64"
-use_lld=true
 use_jumbo_build=true
+use_lld=true