Test PRMX integration

[gburd]

Testing PRMX email bridge functionality

For readability. It was a slight modularity violation to have fields
in PGShmemHeader that were only used by the allocator code in
shmem.c. And it was inconsistent that ShmemLock was nevertheless not
stored there. Moving all the allocator-related fields to a separate
struct makes it more consistent and modular, and removes the need to
allocate and pass ShmemLock separately via BackendParameters.

Merge InitShmemAccess() and InitShmemAllocation() into a single
function that initializes the struct when called from postmaster, and
when called from backends in EXEC_BACKEND mode, re-establishes the
global variables. That's similar to all the *ShmemInit() functions
that we have.

[gburd]

Submitted as pull.19.postgres.1769878402958.gregburd@amazon.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gburd/postgres/ pr-19/gburd/test-prmx-feature-v1

To fetch this version to local tag pr-19/gburd/test-prmx-feature-v1:

git fetch --no-tags https://github.com/gburd/postgres/ tag pr-19/gburd/test-prmx-feature-v1

[gburd]

Submitted as pull.19.v2.postgres.1769880438607.gregburd@amazon.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gburd/postgres/ pr-19/gburd/test-prmx-feature-v2

To fetch this version to local tag pr-19/gburd/test-prmx-feature-v2:

git fetch --no-tags https://github.com/gburd/postgres/ tag pr-19/gburd/test-prmx-feature-v2

[gburd]

/submit

[gburd]

Submitted as pull.19.v3.postgres.1769883484377.gregburd@amazon.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gburd/postgres/ pr-19/gburd/test-prmx-feature-v3

To fetch this version to local tag pr-19/gburd/test-prmx-feature-v3:

git fetch --no-tags https://github.com/gburd/postgres/ tag pr-19/gburd/test-prmx-feature-v3

[gburd]

There is an issue in commit daccdd2:
test: v4 iteration test

• Commit checks stopped - the message is too short

[gburd]

Submitted as pull.19.v4.postgres.1770036351814.gregburd@amazon.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gburd/postgres/ pr-19/gburd/test-prmx-feature-v4

To fetch this version to local tag pr-19/gburd/test-prmx-feature-v4:

git fetch --no-tags https://github.com/gburd/postgres/ tag pr-19/gburd/test-prmx-feature-v4

[gburd]

Interesting, but why?

[gburd]

This is pointless, duh.

[gburd]

Let's take a closer look at what you've done...