fix travis error

Co-authored by: nijincheng@iscas.ac.cn;

Author: ffgan

tools/build_wheel.sh

@@ -2,14 +2,18 @@
 # $INTERFACE64 ("1" or "0")
 # $PLAT (x86_64, i686, arm64, aarch64, s390x, ppc64le)
 
+# The code below is for Travis use only.
+
 set -xe
 
+if [[ ! -e tools/build_prepare.sh ]];then
+    cd /openblas
+fi
+
 source tools/build_prepare.sh
 
 $PYTHON -m pip wheel -w dist -v .
 
-# The code below is for Travis use only.
-
 auditwheel repair -w dist --lib-sdir /lib dist/*.whl
 rm dist/scipy_openblas*-none-any.whl
 # Add an RPATH to libgfortran: