fix gdb path

Author: aswaterman

.travis.yml

@@ -80,6 +80,6 @@ script:
   - ./build.sh
   # Put compiler in expected place for debug tests
   - ln -s $TRAVIS_BUILD_DIR/.build/riscv64-unknown-elf/buildtools/bin/riscv64-unknown-elf-gcc $RISCV/bin
-  - ln -s $TRAVIS_BUILD_DIR/.build/riscv64-unknown-elf/buildtools/bin/riscv64-unknown-elf-gdb $RISCV/bin
+  - ln -s $TRAVIS_BUILD_DIR/.build/riscv64-unknown-elf/build/build-gdb-cross/gdb/gdb $RISCV/bin/riscv64-unknown-elf-gdb
   # Run debug tests
   - PYTHONPATH=$PYTHONPATH:/usr/lib/python2.7/dist-packages make -C riscv-tests/build debug-check