pgsql: Declare AnonymousShmem pointer as "void *".

Declare AnonymousShmem pointer as "void *".

The original coding had it as "PGShmemHeader *", but that doesn't offer any
notational benefit because we don't dereference it. And it was resulting
in compiler warnings on some platforms, notably buildfarm member
castoroides, where mmap() and munmap() are evidently declared to take and
return "char *".

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/81e82643837de93909e0c5a8e14e805f3f69f41e

Modified Files
--------------
src/backend/port/sysv_shmem.c | 13 ++++++-------
1 files changed, 6 insertions(+), 7 deletions(-)