pgsql: jit: Do not try to shut down LLVM state in case of LLVM triggere

jit: Do not try to shut down LLVM state in case of LLVM triggered errors.

If an allocation failed within LLVM it is not safe to call back into LLVM as
LLVM is not generally safe against exceptions / stack-unwinding. Thus errors
while in LLVM code are promoted to FATAL. However llvm_shutdown() did call
back into LLVM even in such cases, while llvm_release_context() was careful
not to do so.

We cannot generally skip shutting down LLVM, as that can break profiling. But
it's OK to do so if there was an error from within LLVM.

Reported-By: Jelte Fennema <Jelte(dot)Fennema(at)microsoft(dot)com>
Author: Andres Freund <andres(at)anarazel(dot)de>
Author: Justin Pryzby <pryzby(at)telsasoft(dot)com>
Discussion: https://postgr.es/m/AM5PR83MB0178C52CCA0A8DEA0207DC14F7FF9@AM5PR83MB0178.EURPRD83.prod.outlook.com
Backpatch: 11-, where jit was introduced

Branch
------
REL_13_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/c49e6f9d974966c7b0fc3eac43a6be922cf6eaee

Modified Files
--------------
src/backend/jit/llvm/llvmjit.c | 18 ++++++++++++++++--
src/backend/jit/llvm/llvmjit_error.cpp | 10 ++++++++++
src/include/jit/llvmjit.h | 1 +
3 files changed, 27 insertions(+), 2 deletions(-)