Future Postgres 15 and Clang 15

<sigh>

Just a note/reminder that "seawasp" has been unhappy for some days now
because of yet another change in the unstable API provided by LLVM:

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=seawasp&dt=2022-06-23%2023%3A18%3A17

llvmjit.c:1115:50: error: use of undeclared identifier 'LLVMJITCSymbolMapPair'
LLVMOrcCSymbolMapPairs symbols = palloc0(sizeof(LLVMJITCSymbolMapPair) * LookupSetSize);

llvmjit.c:1233:81: error: too few arguments to function call, expected 3, have 2
ref_gen = LLVMOrcCreateCustomCAPIDefinitionGenerator(llvm_resolve_symbols, NULL);

The question is: should pg 15 try to be clang 15 ready? I'm afraid yes, as
LLVM does 2 releases per year, so clang 15 should come out this Fall,
together with pg 15. Possibly other changes will come before the
releases:-/

--
Fabien.