Move ndk-common.sh to build/tools/

It doesn't make sense to put it under build/core/ anymore.

Change-Id: I3a63ecabd15d4c34c2ba3800b95246f5eeb6a6f3
diff --git a/ndk-gdb-py b/ndk-gdb-py
index f2a4d94..11643d4 100755
--- a/ndk-gdb-py
+++ b/ndk-gdb-py
@@ -11,7 +11,7 @@
         ;;
 esac
 
-. $PROGDIR/build/core/ndk-common.sh
+. $PROGDIR/build/tools/ndk-common.sh
 
 # -u means unbuffered standard io.
 $PROGDIR/prebuilt/$HOST_TAG/bin/python -u $PROGDIR/ndk-gdb.py "$@"