fix hexdecimal literal string

Fix these warnings only:
```
$ perl -l -e 'print $^V'
v5.16.2
$ perl t/03-pcre-testinput1-06.t  >/dev/null
Illegal hexadecimal digit '\' ignored at (eval 66) line 1, <DATA> line 1.
Illegal hexadecimal digit 'Z' ignored at (eval 66) line 1, <DATA> line 1.
Illegal hexadecimal digit '\' ignored at (eval 67) line 1, <DATA> line 1.
Illegal hexadecimal digit '\' ignored at (eval 70) line 1, <DATA> line 1.
Illegal hexadecimal digit 'Z' ignored at (eval 70) line 1, <DATA> line 1.
```