Replace 'memoffset' crate with core functionality (#12761)

The `std::mem::offset_of` macro was introduced in Rust 1.77.0.

In the passing, mark the function as `const`, as suggested in the
comment. Not sure which compiler version that requires, but it works
with what have currently.

Cargo.lock

@@ -5078,7 +5078,6 @@ dependencies = [
  "criterion",
  "env_logger",
  "log",
- "memoffset 0.9.0",
  "once_cell",
  "postgres",
  "postgres_ffi_types",

Cargo.toml

@@ -135,7 +135,6 @@ lock_api = "0.4.13"
 md5 = "0.7.0"
 measured = { version = "0.0.22", features=["lasso"] }
 measured-process = { version = "0.0.22" }
-memoffset = "0.9"
 moka = { version = "0.12", features = ["sync"] }
 nix = { version = "0.30.1", features = ["dir", "fs", "mman", "process", "socket", "signal", "poll"] }
 # Do not update to >= 7.0.0, at least. The update will have a significant impact

libs/postgres_ffi/Cargo.toml

@@ -12,7 +12,6 @@ crc32c.workspace = true
 criterion.workspace = true
 once_cell.workspace = true
 log.workspace = true
-memoffset.workspace = true
 pprof.workspace = true
 thiserror.workspace = true
 serde.workspace = true

libs/postgres_ffi/src/controlfile_utils.rs

@@ -34,9 +34,8 @@ const SIZEOF_CONTROLDATA: usize = size_of::<ControlFileData>();
 impl ControlFileData {
     /// Compute the offset of the `crc` field within the `ControlFileData` struct.
     /// Equivalent to offsetof(ControlFileData, crc) in C.
-    // Someday this can be const when the right compiler features land.
+    const fn pg_control_crc_offset() -> usize {
-    fn pg_control_crc_offset() -> usize {
+        std::mem::offset_of!(ControlFileData, crc)
-        memoffset::offset_of!(ControlFileData, crc)
     }
 
     ///