Properly install LSan interface header, rely on sanitizer header presence in lit tests

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@183977 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index 700b532..3b39dfa 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -2,6 +2,7 @@
   sanitizer/asan_interface.h
   sanitizer/common_interface_defs.h
   sanitizer/linux_syscall_hooks.h
+  sanitizer/lsan_interface.h
   sanitizer/msan_interface.h)
 
 set(output_dir ${LLVM_BINARY_DIR}/lib/clang/${CLANG_VERSION}/include)