unix: compute libpython shared library name with binary suffix

This should have been done as part of commit
d983b33.

Author: indygreg

cpython-unix/build-cpython.sh

@@ -719,7 +719,7 @@ if [ "${PYBUILD_SHARED}" = "1" ]; then
                 ${ROOT}/out/python/install/bin/python${PYTHON_MAJMIN_VERSION}${PYTHON_BINARY_SUFFIX}
         fi
     else
-        LIBPYTHON_SHARED_LIBRARY_BASENAME=libpython${PYTHON_MAJMIN_VERSION}.so.1.0
+        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}
 
         # If we simply set DT_RUNPATH via --set-rpath, LD_LIBRARY_PATH would be used before