Document LLVM_BUILD_TESTS, LLVM_INCLUDE_TESTS. New convenience target
UnitTests for building all the unit tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117545 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/CMakeLists.txt b/unittests/CMakeLists.txt
index df51bf8..a2eed42 100644
--- a/unittests/CMakeLists.txt
+++ b/unittests/CMakeLists.txt
@@ -10,8 +10,11 @@
     set(EXCLUDE_FROM_ALL ON)
   endif()
   add_llvm_executable(${test_name}Tests ${ARGN})
+  add_dependencies(UnitTests ${test_name}Tests)
 endfunction()
 
+add_custom_target(UnitTests)
+
 include_directories(${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest/include)
 set(LLVM_REQUIRES_RTTI 1)
 add_definitions(-DGTEST_HAS_RTTI=0)