Add support for strlcpy()

Too many places in xrdp use strncpy() to copy strings to fixed-length
buffers, when this is not the correct function to use.

This PR makes sure strlcpy() from the BSDs is available as a saner
alternative. This function is available by default on Linux and FreeBSD.

configure.ac

@@ -238,7 +238,7 @@ AM_COND_IF([DEVEL_DEBUG],
 AC_SEARCH_LIBS([setusercontext], [util])
 
 # Define HAVE_XXXXX macros for some system functions
-AC_CHECK_FUNCS([setusercontext getgrouplist clearenv])
+AC_CHECK_FUNCS([setusercontext getgrouplist clearenv strlcpy])
 
 # The type used by getgrouplist() is the same type used by getgroups()
 AC_TYPE_GETGROUPS