Description of problem:

The following issue is observed in all `ld` versions >= 2.21. Version 2.20 does not exhibit this behavior.

A simple C file:

    #include <stdio.h>
    extern char **environ;
    int main(int argc, char **argv) {
        printf("%p\n", environ);
        return 0;
    }

When compiled, will reference `_environ`:

    $ gcc -o environ environ.c && \
      readelf -s environ | grep " _environ"
         4: 0000000000601040     8 OBJECT  WEAK   DEFAULT   24 _environ.5 (2)
    $

When compiled passing the linker `--gc-sections`, the `_environ` alias is dropped, but the `__environ` and `environ` ones remain:

    $ gcc -Wl,--gc-sections -o environ environ.c && \
      readelf -s environ | grep " _environ"
    $

This breaks glibc functionality that looks at `_environ` internally, because it then points to a different address when the shared object is loaded. This manifested in glibc not respecting memory sub-system environment variables.