pgsql: Fix pg_upgrade failure when extension_control_path is used

Fix pg_upgrade failure when extension_control_path is used

When an extension is located via extension_control_path and it has a
hardcoded $libdir/ path, this is stripped by the
extension_control_path mechanism. But when pg_upgrade verifies the
extension using LOAD, this stripping does not happen, and so
pg_upgrade will fail because it cannot load the extension. To work
around that, change pg_upgrade to itself strip the prefix when it runs
its checks. A test case is also added.

Author: Jonathan Gonzalez V. <jonathan(dot)abdiel(at)gmail(dot)com>
Reviewed-by: Niccolò Fei <niccolo(dot)fei(at)enterprisedb(dot)com>
Reviewed-by: Matheus Alcantara <matheusssilv97(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/43b3691c673a8b9158f5a09f06eacc3c63e2c02d.camel%40gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1e67508730eb0c98bf6eec660d0ed04368982266

Modified Files
--------------
src/bin/pg_upgrade/Makefile | 6 +-
src/bin/pg_upgrade/function.c | 8 ++
src/bin/pg_upgrade/meson.build | 21 +++-
src/bin/pg_upgrade/t/008_extension_control_path.pl | 126 +++++++++++++++++++++
src/test/modules/test_extensions/Makefile | 3 +
src/test/modules/test_extensions/meson.build | 13 +++
src/test/modules/test_extensions/test_ext.c | 22 ++++
7 files changed, 197 insertions(+), 2 deletions(-)