pgsql: Change the way string relopts are allocated.

Change the way string relopts are allocated.

Don't try to allocate the default value for a string relopt in the same
palloc chunk as the relopt_string struct. That didn't work too well if you
added a built-in string relopt in the stringRelOpts array, as it's not
possible to have an initializer for a variable length struct in C. This
makes the code slightly simpler too.

While we're at it, move the call to validator function in
add_string_reloption to before the allocation, so that if someone does pass
a bogus default value, we don't leak memory.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/77949a2913b3cbaa7b2e2a73f014d541e251f18b

Modified Files
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src/backend/access/common/reloptions.c |   39 +++++++++----------------------
src/include/access/reloptions.h        |    2 +-
2 files changed, 13 insertions(+), 28 deletions(-)