/usr/lib/gcc-cross/arm-linux-gnueabihf/4.7/sf/libobjc_gc.so is in libsfobjc-4.7-dev-armhf-cross 4.7.3-11ubuntu1cross1.85.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/arm-linux-gnueabihf/4.7/sf/../../../../../arm-linux-gnueabihf/libsf/libobjc_gc.so.4