Fix MIPS32r2 + DSP2 builders after NDK update.

platform_tools/android/bin/utils/setup_toolchain.sh

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 #!/bin/bash
 #
 # setup_toolchain.sh: Sets toolchain environment variables used by other scripts.
 
 # Fail-fast if anything in the script fails.
@@ skipping 126 matching lines @@
     exportVar CXX "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-clang++"
     exportVar LINK "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-clang"
   fi
 
   exportVar AR "$ANDROID_TOOLCHAIN_PREFIX-ar"
   exportVar RANLIB "$ANDROID_TOOLCHAIN_PREFIX-ranlib"
   exportVar OBJCOPY "$ANDROID_TOOLCHAIN_PREFIX-objcopy"
   exportVar STRIP "$ANDROID_TOOLCHAIN_PREFIX-strip"
 fi
 
+# GCC doesn't seem to put this on its include path when setting -march=mips32r2.
+# Oddly, it does for mips32, mips32r3, and mips32r5, but it's gone again for mips32r6.
+# Clang's fine.
+if [ "$USE_CLANG" != "true" ]; then
+    if [ "$ANDROID_ARCH" == "mips" ]; then
+        exportVar CXX_target "$CXX_target -isystem $ANDROID_TOOLCHAIN/include/c++/4.9.x/mipsel-linux-android"
+    fi
+fi
+
 # Create symlinks for nm & readelf and add them to the path so that the ninja
 # build uses them instead of attempting to use the one on the system.
 # This is required to build using ninja on a Mac.
 if [ $HOST == "darwin" ]; then
   ln -sf $ANDROID_TOOLCHAIN_PREFIX-nm $ANDROID_TOOLCHAIN/bin/nm
   ln -sf $ANDROID_TOOLCHAIN_PREFIX-readelf $ANDROID_TOOLCHAIN/bin/readelf
   ln -sf $ANDROID_TOOLCHAIN_PREFIX-as $ANDROID_TOOLCHAIN/bin/as
 fi
 
 exportVar PATH ${ANDROID_TOOLCHAIN}/bin:${PATH}