pgsql: Check for interrupts during tuple-insertion loops.

Check for interrupts during tuple-insertion loops.

Normally, this won't matter too much; but if I/O is really slow, for
example because the system is overloaded, we might write many pages
before checking for interrupts.  A single toast insertion might
write up to 1GB of data, and a multi-insert could write hundreds
of tuples (and their corresponding TOAST data).

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/c922353b1c7e7fe5fa506664ccf0c87a0abfdda2

Modified Files
--------------
src/backend/access/heap/heapam.c     |    2 ++
src/backend/access/heap/tuptoaster.c |    3 +++
2 files changed, 5 insertions(+)