[PATCH] Return `ERR` with non-positive `set_tabsize(...)`

[Anthony Sottile]

Small demo program:

```c
#include <ncurses.h>

int main() {
    initscr();

    set_tabsize(0);
    mvaddstr(0, 0, "\t*");

    getch();
    endwin();
}
```

Before this would crash with a "Floating point exception"

Signed-off-by: Anthony Sottile <address@hidden>
---
 ncurses/tinfo/lib_setup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/ncurses/tinfo/lib_setup.c b/ncurses/tinfo/lib_setup.c
index b1d1e1ae..23837e51 100644
--- a/ncurses/tinfo/lib_setup.c
+++ b/ncurses/tinfo/lib_setup.c
@@ -173,6 +173,9 @@ NCURSES_EXPORT(int)
 NCURSES_SP_NAME(set_tabsize) (NCURSES_SP_DCLx int value)
 {
     int code = OK;
+    if (value <= 0) {
+       return ERR;
+    }
 #if USE_REENTRANT
     if (SP_PARM) {
        SP_PARM->_TABSIZE = value;
-- 
2.17.1