pgsql: Fix tablespace creation WAL replay to work on Windows.

Fix tablespace creation WAL replay to work on Windows.

The code segment that removes the old symlink (if present) wasn't clued
into the fact that on Windows, symlinks are junction points which have
to be removed with rmdir().

Backpatch to 9.0, where the failing code was introduced.

MauMau, reviewed by Muhammad Asif Naeem and Amit Kapila

Branch
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REL9_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/af7738fe6a33523916a58ac7b276f9467566a439

Modified Files
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src/backend/commands/tablespace.c |   33 +++++++++++++++++++++++++--------
1 file changed, 25 insertions(+), 8 deletions(-)