gdb: pruning more conflict

Yet another directory that conflicts.

```
Linking /usr/local/Cellar/binutils/2.24...
Error: Could not symlink share/info/bfd.info
Target /usr/local/share/info/bfd.info
is a symlink belonging to gdb. You can unlink it:
```
```
Linking /usr/local/Cellar/binutils/2.24...
Error: Could not symlink share/info/configure.info
Target /usr/local/share/info/configure.info
is a symlink belonging to gdb. You can unlink it:
```