Fix more of the build.

Rebase went wrong and the definition of is_arm ended up in a patch
above its first use.

Change-Id: I641ac8301e541c6308ca0a1aea032e406008e6f1
diff --git a/sources/cxx-stl/llvm-libc++/build.py b/sources/cxx-stl/llvm-libc++/build.py
index 682e030..724ff8e 100755
--- a/sources/cxx-stl/llvm-libc++/build.py
+++ b/sources/cxx-stl/llvm-libc++/build.py
@@ -92,6 +92,7 @@
     for abi in abis:
         static_lib_dir = os.path.join(obj_out, 'local', abi)
         install_dir = os.path.join(lib_out, abi)
+        is_arm = abi.startswith('armeabi')
 
         if is_arm:
             shutil.copy2(