Fixes for w3m formula

- Add missing build dependency on gettext
- Build against brewed openssl

Here is the error I get for missing gettext:
```
==> Downloading https://downloads.sourceforge.net/project/w3m/w3m/w3m-0.5.3/w3m-0.5.3.tar.gz
Already downloaded: /Library/Caches/Homebrew/w3m-0.5.3.tar.gz
==> Patching
patching file main.c
==> ./configure --prefix=/usr/local/Cellar/w3m/0.5.3 --disable-image
==> make install
rm -f ja.gmo && : -c --statistics --verbose -o ja.gmo ja.po
mv: rename t-ja.gmo to ja.gmo: No such file or directory
make[2]: *** [ja.gmo] Error 1
make[1]: *** [stamp-po] Error 2
make: *** [install-po] Error 2
```