Log Message:
utf8proc: update to 2.4.0.

## Version 2.4 ##

2019-05-10

- Unicode 12.1 support ([#156]).

- New `-DUTF8PROC_INSTALL=No` option for `cmake` builds to disable installation \ 
([#152]).

- Better `make` support for HP-UX ([#154]).

- Fixed incorrect `UTF8PROC_VERSION_MINOR` version number in header and bumped \ 
shared-library version.