Let gyp_chromium set GYP_CROSSCOMPILE for android and ios.

build/android/envsetup.sh

Index: build/android/envsetup.sh
diff --git a/build/android/envsetup.sh b/build/android/envsetup.sh
index 1581c8c93a8137e81917882f49c216963ad3bf64..6286a1e1f921a7a4eff30fd21f9c23e5480f9026 100755
--- a/build/android/envsetup.sh
+++ b/build/android/envsetup.sh
@@ -87,14 +87,9 @@ export GYP_DEFINES="${DEFINES}"
 # Source a bunch of helper functions
 . ${CHROME_SRC}/build/android/adb_device_functions.sh
 
-# Declare Android are cross compile.
-export GYP_CROSSCOMPILE=1
-
 # Performs a gyp_chromium run to convert gyp->Makefile for android code.
 android_gyp() {
   # This is just a simple wrapper of gyp_chromium, please don't add anything
   # in this function.
-  (
-    "${CHROME_SRC}/build/gyp_chromium" --depth="${CHROME_SRC}" --check "$@"
-  )
+  "${CHROME_SRC}/build/gyp_chromium" --depth="${CHROME_SRC}" --check "$@"
 }