pgsql: Split out list of XLog resource managers

Split out list of XLog resource managers

The new rmgrlist.h header, containing all necessary data
about built-in resource managers, allows other pieces of code to
access them.

In particular, this allows a future pg_xlogdump program to extract
rm_desc function pointers, without having to keep a duplicate list of
them.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/5a1cd89f8f4a0bc13c85810de47d48bb6386ea89

Modified Files
--------------
src/backend/access/transam/rmgr.c | 21 +++--------------
src/include/access/rmgr.h | 36 +++++++++++++----------------
src/include/access/rmgrlist.h | 44 ++++++++++++++++++++++++++++++++++++
src/include/access/xlog_internal.h | 5 +++-
4 files changed, 68 insertions(+), 38 deletions(-)