[patch, fortran] Partial fix for PR97454, declarations of some library functions

[Thomas Koenig]

Hi Paul,

> OK for master.

Committed, thanks.

> Thanks for working on this one!

There is still a lto to do (I left in this typo by
design :-), especially with cshift and friends.  Let's see
how far I can progress until gcc 11 with this one, if helping
out Nicolas with coarray stuff leaves me time for that.

Best regards

	Thomas