pgsql: In pg_upgrade, rename macro EXEC_EXT to SHELL_EXT for clarity.

In pg_upgrade, rename macro EXEC_EXT to SHELL_EXT for clarity.

Backpatch to 9.0.X.

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=fc8470ed4d7aca48b14521168d607ef8bbdcf0e1

Modified Files
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contrib/pg_upgrade/check.c | 2 +-
contrib/pg_upgrade/pg_upgrade.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)