The page footer line (psmarg) is created in ps_begin(), and the

The page footer line (psmarg) is created in ps_begin(), and the
last call writing to it is always ps_endline(), which ends with
ps_pclose(), which prints "ET" (end text).

Consequently, do not print another instance of "ET" in ps_closepage()
after the footer line and before the "endstream" for the page.

Fixing a PDF syntax error found while investigating the bug report
from Jan Stary that also resulted in the previous commit.