shell: improve bash compatibility of read built-in

Make the read built-in more compatible with bash:

- Return an exit code of 142 on timeout.

- When the timeout expires before a newline is detected in the
  input bash captures the partial input.  This behaviour is new
  since bash version 4.4.  BusyBox shells had the pre-4.4 behaviour
  where the input was lost.

Update the tests to suit and fix a couple of compiler errors in
the testsuite.

function                                             old     new   delta
builtin_read                                         154     174     +20
readcmd                                              213     228     +15
shell_builtin_read                                  1364    1370      +6
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 41/0)               Total: 41 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

0 files changed, 0 insertions, 0 deletions