Avoid a "condition always true" warning on platforms where char
is unsigned by default, such as PowerPC and ARM.

* subversion/libsvn_subr/utf_validate.c
  (first_non_fsm_start_char, first_non_fsm_start_char_cstring):
   Add explicit cast to avoid warning when plain char is unsigned.

Approved by: Philip Martin


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1468255 13f79535-47bb-0310-9956-ffa450edef68