Remove mutex around LLVM calls from booster

[jberthold]

Previously the LLVM backend was not thread-safe so the simplification calls had to be sequentialised for concurrent RPC requests.

Since thread-local storage is now used, the calls can be executed concurrently/in parallel using multiple cores. This PR removes the mutex that sequentialised the calls before.

This change should be tested in combination with K release 7.1.198 or higher (LLVM backend using thread-local storage).

[jberthold]

No significant performance changes to KEVM or kontrol tests

Test	enable-parallel-calls-to-llvm time	master-f6e0f33aa time	(enable-parallel-calls-to-llvm/master-f6e0f33aa) time
mcd/end-subuu-pass-spec.k	54.05	55.96	0.965868477483917
erc20/ds/transferFrom-success-2-spec.k	60.64	58.56	1.03551912568306
kontrol/test-expectreverttest-test_expectrevert_bytes4-0-spec.k	65.84	63.47	1.037340475815346
TOTAL	180.53	177.99	1.0142704646328444

Test	enable-parallel-calls-to-llvm time	master-f6e0f33aa time	(enable-parallel-calls-to-llvm/master-f6e0f33aa) time
kontrol/src/tests/integration/test_foundry_prove.py::test_foundry_xml_report	18.98	28.23	0.6723343960325895
FreshCheatcodes.test_freshSymbolicWord()	12.32	15.59	0.7902501603592046
ExternalLibTest.testSum()	15.86	18.73	0.8467698878804057
PlainPrankTest.test_prank_zeroAddress_true()	20.02	22.95	0.8723311546840958
StoreTest.testStoreLoadNonExistent()	12.56	14.09	0.8914123491838184
EmitContractTest.testExpectEmitDoNotCheckData()	15.55	17.39	0.8941920644048303
ExpectRevertTest.testFail_ExpectRevert_failAndSuccess()	18.29	20.44	0.8948140900195694
ExpectRevertTest.test_expectRevert_bytes4()	17.81	19.88	0.8958752515090543
StoreTest.testLoadNonExistent()	12.22	13.44	0.9092261904761906
MockCallTestFoundry.testMockGetters()	33.13	36.33	0.9119185246352878
CounterTest.testSetNumber(uint256)	20.59	22.38	0.920017873100983
ExpectRevertTest.test_expectRevert_returnValue()	20.98	22.78	0.9209833187006146
AssertTest.checkFail_assert_false()	16.09	17.35	0.9273775216138328
MockCallTestFoundry.testMockCalldata()	35.83	38.3	0.9355091383812011
AssertTest.test_assert_false()	29.11	31.02	0.9384268214055448
kontrol/src/tests/integration/test_foundry_prove.py::test_foundry_merge_nodes	28.58	30.45	0.9385878489326764
BlockParamsTest.testBlockNumber()	11.59	12.34	0.9392220421393841
CoinBaseTest.test_coinbase_setup()	23.77	24.87	0.9557700040209086
LabelTest.testLabel()	12.12	11.7	1.035897435897436
PlainPrankTest.test_startPrankWithOrigin_true()	18.09	17.46	1.036082474226804
ExpectRevertTest.testFail_expectRevert_false()	18.6	17.95	1.0362116991643455
Setup2Test.testFail_setup()	27.36	26.23	1.043080442241708
AddrTest.test_addr_true()-trace_options1	18.49	17.72	1.0434537246049662
AssumeTest.test_assume_staticCall(bool)	14.49	13.81	1.0492396813902969
AssertTest.prove_assert_true()	12.32	11.72	1.0511945392491466
AssertTest.test_revert_branch(uint256,uint256)	48.94	46.48	1.0529259896729777
AssertTest.test_failing_branch(uint256)	46.9	44.47	1.0546435799415337
ImmutableVarsTest.test_run_deployment(uint256)	147.35	139.56	1.0558182860418457
kontrol/src/tests/integration/test_foundry_prove.py::test_foundry_show_with_hex_encoding	5.31	5.02	1.0577689243027888
],bytes32)))	13.48	12.74	1.0580847723704867
AssertTest.testFail_expect_revert()	46.65	44.08	1.0583030852994555
kontrol/src/tests/integration/test_foundry_prove.py::test_constructor_with_symbolic_args	59.74	55.77	1.071185225031379
AssumeTest.testFail_assume_false(uint256,uint256)	36.42	33.94	1.0730701237477904
ChainIdTest.test_chainid_setup()	25.18	23.34	1.078834618680377
kontrol/src/tests/integration/test_foundry_prove.py::test_foundry_extra_lemmas	168.57	155.5	1.0840514469453375
MockFunctionTest.test_mock_function_concrete_args()	42.36	39.02	1.0855971296770885
SymbolicStorageTest.testFail_SymbolicStorage(uint256)	39.81	36.24	1.0985099337748345
ExternalLibTest.testSquare(uint256)	28.95	26.32	1.0999240121580547
AssumeTest.testFail_assume_true(uint256,uint256)	34.37	31.22	1.100896860986547
],uint256))	26.75	24.2	1.1053719008264462
StoreTest.testStoreLoad()	15.59	13.96	1.1167621776504297
BlockParamsTest.testChainId(uint256)	13.87	12.39	1.1194511702986278
CounterTest.testIncrement()	21.18	18.83	1.124800849707913
MockCallTestFoundry.testMockSelector()	29.79	26.47	1.1254250094446543
ExpectRevertTest.testFail_expectRevert_bytes4()	23.0	20.41	1.1268985791278785
MockCallTest.testSelectorMockCall()	27.57	24.19	1.1397271599834642
ExpectCallTest.testExpectRegularCall()	19.25	16.86	1.141755634638197
ExpectRevertTest.test_expectRevert_message()	20.59	18.01	1.1432537479178233
EmitContractTest.testExpectEmit()	17.69	15.31	1.1554539516655782
AssertTest.test_assert_true_branch(uint256)	29.86	25.32	1.179304897314376
kontrol/src/tests/integration/test_foundry_prove.py::test_foundry_remove_node	11.47	9.39	1.2215122470713524
FreshCheatcodes.test_bool()	15.58	12.37	1.2594987873888441
StoreTest.testGasStoreWarmUp()	19.49	15.42	1.2639429312581063
TOTAL	1520.46	1469.98	1.0343406032735138