[PATCH] Make ginsh evaluate line-by-line in non-interactive mode.

[PATCH] Make ginsh evaluate line-by-line in non-interactive mode.

When used interactively ginsh consumes the input line-by-line, so
if a complete expression is entered it is enough to end the line
to get an evaluated result. In the non-interative mode (i.e. if
the input is not a tty) the input is consumed in blocks, making
it impossible to use ginsh as a subprocess.

This patch makes the non-interactive mode reuse the same line
parsing logic as the interactive mode (without readline), but skips
printing the "> " prompt, preserving the backward compatibility.