Fix narrow-to-defun in f90-mode

* lisp/progmodes/f90.el (f90-beginning-of-subprogram): Make
narrow-to-defun work better (bug#44042).
1 job for master in 82 minutes and 52 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
passed #8313
test-all

01:22:52