Fix MIPS32r2 + DSP2 builders after NDK update.

platform_tools/android/bin/utils/setup_toolchain.sh

Index: platform_tools/android/bin/utils/setup_toolchain.sh
diff --git a/platform_tools/android/bin/utils/setup_toolchain.sh b/platform_tools/android/bin/utils/setup_toolchain.sh
index ebeab27a5031bcf0d89694134fc8d287d9dbd9fa..c341c2e341ac61538afcc90037ee0767308cb98d 100755
--- a/platform_tools/android/bin/utils/setup_toolchain.sh
+++ b/platform_tools/android/bin/utils/setup_toolchain.sh
@@ -144,6 +144,15 @@ else
   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.