[CMake] Move LLDB_TEST_BUILD_DIRECTORY into test/CMakeLists.txt

The LLDB_TEST_BUILD_DIRECTORY variable only matters to the different
test suites. Therefore they belong in test/CMakeLists.txt rather than
the top-level CMakeLists.txt.

Author: JDevlieghere

lldb/CMakeLists.txt

@@ -81,8 +81,6 @@ add_subdirectory(docs)
 
 option(LLDB_INCLUDE_TESTS "Generate build targets for the LLDB unit tests." ${LLVM_INCLUDE_TESTS})
 if(LLDB_INCLUDE_TESTS)
-  set(LLDB_TEST_BUILD_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/lldb-test-build.noindex" CACHE PATH "The build root for building tests.")
-
   add_subdirectory(test)
   add_subdirectory(unittests)
   add_subdirectory(utils/lit-cpuid)

lldb/test/CMakeLists.txt

@@ -1,6 +1,9 @@
 # Test runner infrastructure for LLDB. This configures the LLDB test trees
 # for use by Lit, and delegates to LLVM's lit test handlers.
 
+# Configure the build directory.
+set(LLDB_TEST_BUILD_DIRECTORY "${PROJECT_BINARY_DIR}/lldb-test-build.noindex" CACHE PATH "The build root for building tests.")
+
 # Configure and create module cache directories.
 set(LLDB_TEST_MODULE_CACHE_LLDB "${LLDB_TEST_BUILD_DIRECTORY}/module-cache-lldb" CACHE PATH "The Clang module cache used by the Clang embedded in LLDB while running tests.")
 set(LLDB_TEST_MODULE_CACHE_CLANG "${LLDB_TEST_BUILD_DIRECTORY}/module-cache-clang" CACHE PATH "The Clang module cache used by the Clang while building tests.")