pgsql: Change fmgr.h typedefs to use original names

Change fmgr.h typedefs to use original names

fmgr.h defined some types such as fmNodePtr which is just Node *, but
it made its own types to avoid having to include various header files.
With C11, we can now instead typedef the original names without fear
of conflicts.

Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/10d32190-f31b-40a5-b177-11db55597355(at)eisentraut(dot)org

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/4bd91912987d794c48dd4ba4c337906bd23759be

Modified Files
--------------
src/backend/utils/fmgr/fmgr.c | 5 ++---
src/include/fmgr.h | 30 +++++++++++++++---------------
src/include/utils/builtins.h | 2 +-
src/tools/pgindent/typedefs.list | 4 ----
4 files changed, 18 insertions(+), 23 deletions(-)