CVE-2019-15547: Mishandling of format strings in ncurses

ncurses exposes functions from the ncurses library which:

• Pass buffers without length to C functions that may write an arbitrary amount of data, leading to a buffer overflow. (instr, mvwinstr, etc)
• Passes rust &str to strings expecting C format arguments, allowing hostile input to execute a format string attack, which trivially allows writing arbitrary data to stack memory (functions in the printw family).