From: Hugh Dickins <hugh@veritas.com>, Christoph Rohland <cr@sap.com>

Switches the long GPL blurb which Hugh took from the 2.4-ac version of
mm/shmem.c, back to the original oneliner (as in 2.4.current).

Christoph spotted that the long blurb says "either version 2 of the License,
or (at your option) any later version", whereas he intended it be as COPYING
says, version 2 period.  Hugh and Christoph are happier with known version 2
than undefined future variants.