Fix build of textproc/qt4-clucene on aarch64. The error message is similar
to a lot of the recent clang6 fixes, but doesn't show up on amd64:

../../../../src/3rdparty/clucene/src/CLucene/queryParser/Lexer.cpp:120:23:

error: non-constant -expression cannot be narrowed from type 'int' to
'wchar_t' in initializer list [-Wc++11-narrowing]

This only becomes visible now that Qt4 atomics are fixed on aarch64
and the build gets to this point.

Bump PORTREVISION to be on the safe side: it's a code change, after all.

Approved by: tcberner (mentor)
Differential Revision: https://reviews.freebsd.org/D13991