[CMake] Log output of configure/build/install steps for instrumented libcxx to reduce noise

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@208632 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/cmake/Modules/AddCompilerRT.cmake b/cmake/Modules/AddCompilerRT.cmake
index 5b3b740..781e757 100644
--- a/cmake/Modules/AddCompilerRT.cmake
+++ b/cmake/Modules/AddCompilerRT.cmake
@@ -200,6 +200,9 @@
                -DCMAKE_CXX_FLAGS=${LIBCXX_CFLAGS}
                -DCMAKE_BUILD_TYPE=Release
                -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
+    LOG_BUILD 1
+    LOG_CONFIGURE 1
+    LOG_INSTALL 1
     )
 
   ExternalProject_Add_Step(${name} force-reconfigure