Fix the ninja build on mac to use nm/readelf from the Android toolchain instead of the host system.

platform_tools/android/bin/android_setup.sh

Index: platform_tools/android/bin/android_setup.sh
diff --git a/platform_tools/android/bin/android_setup.sh b/platform_tools/android/bin/android_setup.sh
index 7a44317e872d06c070a38d38acc8fea2f582ac6c..d29a07048bf8dfa99c20aa0f5227d09cdfce43f4 100755
--- a/platform_tools/android/bin/android_setup.sh
+++ b/platform_tools/android/bin/android_setup.sh
@@ -152,6 +152,13 @@ setup_toolchain() {
   export RANLIB="$ANDROID_TOOLCHAIN_PREFIX-ranlib"
   export OBJCOPY="$ANDROID_TOOLCHAIN_PREFIX-objcopy"
   export STRIP="$ANDROID_TOOLCHAIN_PREFIX-strip"
+  
+  # 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
+  ln -sf $ANDROID_TOOLCHAIN_PREFIX-nm $ANDROID_TOOLCHAIN/nm
+  ln -sf $ANDROID_TOOLCHAIN_PREFIX-readelf $ANDROID_TOOLCHAIN/readelf
+  export PATH=$ANDROID_TOOLCHAIN:$PATH
+  
 }
 
 # Helper function to configure the GYP defines to the appropriate values