[orc][cmake] Check if 8 byte atomics require libatomic for unittest

rL319838 introduced SymbolStringPool which uses 8 byte atomics for
reference counters. On systems which do not support such atomics
natively such as MIPS32, explicitly add libatomic as one of the
libraries for SymbolStringPool's unittest.

Reviewers: lhames, beanz

Differential Revision: https://reviews.llvm.org/D41010


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321225 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Simon Dardis

unittests/ExecutionEngine/Orc/CMakeLists.txt

@@ -24,4 +24,9 @@ add_llvm_unittest(OrcJITTests
   SymbolStringPoolTest.cpp
   )
 
-target_link_libraries(OrcJITTests PRIVATE ${LLVM_PTHREAD_LIB})
+set(ORC_JIT_TEST_LIBS ${LLVM_PTHREAD_LIB})
+if(NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB)
+  list(APPEND ORC_JIT_TEST_LIBS atomic)
+endif()
+
+target_link_libraries(OrcJITTests PRIVATE ${ORC_JIT_TEST_LIBS})