resolveSubtable: Fix buffer overflow parsing a malformed table
resolveSubtable: Fix buffer overflow parsing a malformed table

The subtable's name can theoretically be up to MAXSTRING characters long.
The base name is then copied into a buffer, and the subtable's name is
appended, so we should allocate more than MAXSTRING bytes for the buffer.

Fixes CVE-2017-13739, CVE-2017-13740, and CVE-2017-13742.

BueVest/liblouis,IndexBraille/liblouis,hammera/liblouis,IndexBraille/liblouis,liblouis/liblouis,BueVest/liblouis,hammera/liblouis,hammera/liblouis,BueVest/liblouis,BueVest/liblouis,BueVest/liblouis,IndexBraille/liblouis,BueVest/liblouis,liblouis/liblouis,liblouis/liblouis,liblouis/liblouis,IndexBraille/liblouis,liblouis/liblouis,liblouis/liblouis,hammera/liblouis,IndexBraille/liblouis,hammera/liblouis,hammera/liblouis