library: relocate the typedef used in alloc.h override

library: relocate the typedef used in alloc.h override

There is no longer justification for placing a typedef
employed in overriding that alloc.h message handler in
the procps.h header file. So this commit just moves it
to the alloc.h header file itself where's it's needed!

[ gosh, sure wish i had thought to relocate this guy ]
[ when the changes in the 1st commit shown were made ]

Reference(s):
. most recent related changes
commit 18e5aecd2b61387ebd82c83f6f716e4c8e093272
. place where it *should* have been relocated
commit 2865ded64e72e0bec721dad9b442dab0899ee2b0

Signed-off-by: Jim Warner <james.warner@comcast.net>