Make build recipe POSIX sh compatible

nftables.spec

@@ -102,24 +102,23 @@ mkdir bin
 ln -s "%_bindir/docbook-to-man" bin/docbook2x-man
 export PATH="$PATH:$PWD/bin"
 mkdir obj
-pushd obj/
+cd obj/
 %define _configure ../configure
 %configure --disable-silent-rules --disable-static --docdir="%_docdir/%name" \
 	--includedir="%_includedir/%name" --with-json \
 	--enable-python --with-python-bin="$(which python3)"
 %make_build
-popd
-pushd py
+cd -
+cd py
 %pyproject_wheel
-popd
+cd -
 
 %install
 b="%buildroot"
 %make_install -C obj
-pushd py
+cd py
 %pyproject_install
 %python_expand %fdupes %buildroot/%{$python_sitelib}
-popd
 rm -f "%buildroot/%_libdir"/*.la
 mkdir -p "$b/%_docdir/%name/examples"
 mv -v "$b/%_datadir/nftables"/*.nft "$b/%_docdir/%name/examples/"