[OrderFiles] Don't allow lit to run dtrace multithreaded

Dtrace is implemented to try and minimize performance impact on the process being traced. This results in dtrace dropping samples if it is taking too many CPU resources. Multi-threading dtrace increases the sample drop rate dramatically.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@266213 91177308-0d34-0410-b5e6-96231b3b80d8

utils/perf-training/CMakeLists.txt

@@ -48,6 +48,7 @@ if(DTRACE)
 
   add_lit_testsuite(generate-dtrace-logs "Generating clang dtrace data"
     ${CMAKE_CURRENT_BINARY_DIR}/order-files/
+    ARGS -j 1
     DEPENDS clang clear-dtrace-logs
     )