BUG #14277: when define USE_NAMED_POSIX_SEMAPHORES , make error

The following bug has been logged on the website:

Bug reference: 14277
Logged by: Zhou Digoal
Email address: digoal(at)126(dot)com
PostgreSQL version: 9.5.3
Operating system: CentOS 7.x x64
Description:

when i define
USE_NAMED_POSIX_SEMAPHORES, then make.

```
CFLAGS=-DUSE_NAMED_POSIX_SEMAPHORES ./configure
--prefix=/home/digoal/pgsql9.5
```

make error:
```
gmake[4]: Entering directory
`/home/digoal/postgresql-9.5.3/src/backend/access/heap'
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement
-Wendif-labels -Wmissing-format-attribute -Wformat-security
-fno-strict-aliasing -fwrapv -fexcess-precision=standard
-DUSE_NAMED_POSIX_SEMAPHORES -I../../../../src/include -D_GNU_SOURCE -c -o
heapam.o heapam.c
In file included from ../../../../src/include/storage/proc.h:21:0,
from ../../../../src/include/storage/shm_mq.h:18,
from ../../../../src/include/access/parallel.h:20,
from heapam.c:45:
../../../../src/include/storage/pg_sema.h:54:3: error: conflicting types for
‘PGSemaphoreData’
} PGSemaphoreData;
^
../../../../src/include/storage/pg_sema.h:38:16: note: previous declaration
of ‘PGSemaphoreData’ was here
typedef sem_t *PGSemaphoreData;
^
gmake[4]: *** [heapam.o] Error 1
gmake[4]: Leaving directory
`/home/digoal/postgresql-9.5.3/src/backend/access/heap'
gmake[3]: *** [heap-recursive] Error 2
gmake[3]: Leaving directory
`/home/digoal/postgresql-9.5.3/src/backend/access'
gmake[2]: *** [access-recursive] Error 2
gmake[2]: Leaving directory `/home/digoal/postgresql-9.5.3/src/backend'
gmake[1]: *** [all-backend-recurse] Error 2
gmake[1]: Leaving directory `/home/digoal/postgresql-9.5.3/src'
gmake: *** [all-src-recurse] Error 2
```