pgsql: Reorder actions in ProcArrayApplyRecoveryInfo()

Reorder actions in ProcArrayApplyRecoveryInfo()

Since 5a1dfde8334b, 2PC filenames use FullTransactionId. Thus, it needs to
convert TransactionId to FullTransactionId in StandbyTransactionIdIsPrepared()
using TransamVariables->nextXid. However, ProcArrayApplyRecoveryInfo()
first releases locks with usage StandbyTransactionIdIsPrepared(), then advances
TransamVariables->nextXid. This sequence of actions could cause errors.
This commit makes ProcArrayApplyRecoveryInfo() advance
TransamVariables->nextXid before releasing locks.

Reported-by: Thomas Munro, Michael Paquier
Discussion: https://postgr.es/m/CA%2BhUKGLj_ve1_pNAnxwYU9rDcv7GOhsYXJt7jMKSA%3D5-6ss-Cw%40mail.gmail.com
Discussion: https://postgr.es/m/Zadp9f4E1MYvMJqe%40paquier.xyz

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/c64086b79dbad19e4ee0af8d19e835111aa87bd5

Modified Files
--------------
src/backend/storage/ipc/procarray.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)