its: Fix test failure.
* gettext-tools/src/its.c (normalize_whitespace): Fix detection of paragraph
boundary. Get rid of initial trim() call.
* gettext-tools/tests/xgettext-its-1: Fix typo. Verify removal of whitespace
at the end of the last paragraph.
* autogen.sh (GNULIB_MODULES_TOOLS_FOR_SRC): Add memchr.
