Add more options for possible symbol names.

It looks like some OS's have extra underscores in the symbol names for the libicuuc functions.  I am  using CentOS 6 and get this:

```
$ readelf -Ws /usr/lib64/libicuuc.so.42 | awk '{print $8}' | grep ucasemap_open
ucasemap_open_4_2
```

This commit just adds some more options to work for this type of numbering.