Don't dump llvm-config --cmakedir output if command fails.

This patch adjusts the out-of-tree CMake configuration so that
the stderr output is ignored when an old llvm-config is found
that doesn't support --cmakedir.


git-svn-id: https://llvm.org/svn/llvm-project/libunwind/trunk@291992 91177308-0d34-0410-b5e6-96231b3b80d8

Author: EricWF

CMakeLists.txt

@@ -49,7 +49,8 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
     execute_process(
       COMMAND ${LLVM_CONFIG_PATH} --cmakedir
       RESULT_VARIABLE HAD_ERROR
-      OUTPUT_VARIABLE CONFIG_OUTPUT)
+      OUTPUT_VARIABLE CONFIG_OUTPUT
+      ERROR_QUIET)
     if(NOT HAD_ERROR)
       string(STRIP "${CONFIG_OUTPUT}" LLVM_CMAKE_PATH)
     else()