fixup! Build libtcl

Author: geofft

cpython-unix/build-cpython.sh

@@ -705,6 +705,8 @@ if [ "${PYBUILD_SHARED}" = "1" ]; then
             ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}
 
         # Python's build system doesn't make this file writable.
+        # TODO(geofft): @executable_path/ is a weird choice here, who is
+        # relying on it? Should probably be @loader_path.
         chmod 755 ${ROOT}/out/python/install/lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}
         install_name_tool \
             -change /install/lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME} @executable_path/${LIBPYTHON_SHARED_LIBRARY_BASENAME} \
@@ -723,6 +725,13 @@ if [ "${PYBUILD_SHARED}" = "1" ]; then
                 -change /install/lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME} @executable_path/../lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME} \
                 ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}
         fi
+
+        # At the moment, python3 and libpython don't have shared-library
+        # dependencies, but at some point we will want to run this for
+        # them too.
+        for module in ${ROOT}/out/python/install/lib/python*/lib-dynload/*.so; do
+            install_name_tool -rpath @loader_path/../.. "$module"
+        done
     else # (not macos)
         LIBPYTHON_SHARED_LIBRARY_BASENAME=libpython${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}.so.1.0
         LIBPYTHON_SHARED_LIBRARY=${ROOT}/out/python/install/lib/${LIBPYTHON_SHARED_LIBRARY_BASENAME}