changing terminal-width while program is running

[Sven Koehler]

Hi,

if you use bash inside an xterm, bash usually is informed when the width
of the terminal-window changes, but if you change the terminal's width
while a program is running, bash still has the old terminal-width in mind
when the program exists.

Steps to reproduce:
- start bash inside an xterm
- execute "sleep 10"
- change width of the terminal while "sleep 10" is executed
- try to type a long command when the bash-prompt is there again

Actual Result:
- the text is not wrapped correctly to the current width of the terminal

Expected Result:
- bash should ask for the terminal's current width when displaying the
prompt. than the text would be wrapped correctly