Added a mapping for a missing mbrola phoneme in polish-mbrola-1. (#1696)

Small change to improve the `polish-mbrola-1` voice.
Previously it would produce:
```
$ espeak -v polish-mbrola-1 "Wiewiórka siedzi na drzewie i je orzech."
mbrola: Warning: j-E# unknown, replaced with _-_
mbrola: Warning: E#-_ unknown, replaced with _-_
```

Now it correctly synthesizes the audio.

phsource/mbrola/pl1

 0  a#  NULL  0  a
 0  y   NULL  0  I
 0  E   NULL  0  e
+0  E#  NULL  0  e
 0  O   NULL  0  o
 0  O~  NULL  0  o~
 0  E~  NULL  0  e~