[lldb] Restore default setting of LLDB_INCLUDE_TESTS in standalone builds

In 52f39853ab the option LLDB_INCLUDE_TESTS was
moved above the inclusion of LLDBStandalone. This isn't a problem per-se, but
it changes the default value of LLDB_INCLUDE_TESTS in standalone builds.
LLDBStandalone explicitly sets LLVM_INCLUDE_TESTS to true, indicating that
for standalone builds this is considered the default behavior.
This patch restores said default behavior.

Differential Revision: https://reviews.llvm.org/D138237

lldb/CMakeLists.txt

@@ -18,6 +18,7 @@ set(CMAKE_MODULE_PATH
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(lldb)
   set(LLDB_BUILT_STANDALONE TRUE)
+  set(LLVM_INCLUDE_TESTS ON CACHE INTERNAL "")
 endif()
 
 # Must go below project(..)

lldb/cmake/modules/LLDBStandalone.cmake

@@ -89,7 +89,6 @@ include(CheckAtomic)
 include(LLVMDistributionSupport)
 
 set(PACKAGE_VERSION "${LLVM_PACKAGE_VERSION}")
-set(LLVM_INCLUDE_TESTS ON CACHE INTERNAL "")
 
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
 include_directories(