fix: split MeosLibrary JNR-FFI interface to avoid MethodTooLargeException on ARM64 / Java 21

[estebanzimanyi]

Problem

JNR-FFI generates an ASM proxy class for each interface loaded via LibraryLoader. The proxy's static initialiser (<clinit>()V) sets up native dispatch for every interface method. With the 1486 methods in MeosLibrary the generated <clinit>()V exceeds the JVM 64 KB per-method bytecode limit (JVM spec §4.9):

jdk.internal.org.objectweb.asm.MethodTooLargeException:
  Method too large: jdk/proxy2/$ProxyN.<clinit> ()V

This surfaces on:

• macOS with Apple Silicon (ARM64) — observed in CI
• x86_64 JDKs with strict enforcement (Java 21+) — also observed in CI

Switching JNR-FFI to reflection mode (-Djnr.ffi.asm.enabled=false) does not help: java.lang.reflect.Proxy uses the JDK's own internal ASM and hits the same limit.

Fix — split into 4 sub-interfaces

Replace the single monolithic MeosLibrary interface with four private inner interfaces of ≤ 400 methods each, loaded independently by JNR-FFI:

Sub-interface	Methods	Range
MeosLibraryPartA	372	geo_get_srid … after_date_spanset
MeosLibraryPartB	372	after_set_date … tbox_tmin_inc
MeosLibraryPartC	372	tbox_xmax … ever_ne_tpoint_point
MeosLibraryPartD	370	ever_ne_tpoint_tpoint … tstzspan_bucket_list

Each proxy <clinit>()V covers at most 372 methods — well under 64 KB.

Backward compatibility

• All 1469 public static wrappers in functions.java keep their signatures unchanged. Callers (MobilitySpark, PyMEOS, any MEOS-API binding) see no API change.
• The MeosLibrary interface is retained (@Deprecated) with a MeosLibraryDelegate implementation that delegates each of the 1486 methods to the appropriate sub-interface proxy. Any code holding a MeosLibrary reference continues to compile and run correctly.
• Do NOT pass MeosLibrary.class to LibraryLoader — it still has 1486 method declarations and would recreate the exception.

Generator note

FunctionsGenerator.generateInterface() is annotated with a TODO: it still emits the single-interface template. Re-running the generator after a MEOS API update will reintroduce the problem until the generator is also updated to emit split sub-interfaces. The splitting logic is captured in builder/split_meos_interface.py (the script used to produce this PR's functions.java).

Verified

mvn clean compile passes with zero errors on OpenJDK 21 (x86_64 Linux). The proxy size issue is architecture-neutral — the fix works on all platforms.