Revert "Use struct to enforce relative location of local variables in the stack frame."

This reverts commit 651808b012fdbce75a861df64bea4666d62ac6e9.
Fix apparent typo in call to utf82u_strncpy.

The original author must have meant ubuf+1 and not ubuf-1, in order to
preserve the space previously inserted at index 0 of ubuf[].