Make after-change-functions called from call-process get the correct BEG

This fixes bug #39585.

* src/callproc.c (call_process): Supply the correct CHARPOS to
signal_after_change (twice).
1 job for emacs-27 in 62 minutes and 56 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #4997
test-all

01:02:56