pgsql: Now that the shared library name can be adjusted in the library

Now that the shared library name can be adjusted in the library test,
have pg_upgrade allocate a maximum fixed size buffer for testing the
library file name, rather than base the allocation on the library name.

Backpatch to 9.1.

Branch
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REL9_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/e96fcb06b9721f975daed229c0c61f283d320357

Modified Files
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contrib/pg_upgrade/function.c |    3 +--
1 files changed, 1 insertions(+), 2 deletions(-)