LIBCXXABI_TARGET_TRIPLE won't always be set.

Fixes issue with r226235. Build configuration difference between
libc++ and libc++abi.

llvm-svn: 226240

diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
index 4dc160a..63301e7 100644 (file)
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -247,7 +247,8 @@ if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 endif()
 
-list(APPEND LIBCXXABI_COMPILE_FLAGS "-target ${LIBCXXABI_TARGET_TRIPLE}")
+append_if(LIBCXXABI_COMPILE_FLAGS LIBCXXABI_TARGET_TRIPLE
+          "-target ${LIBCXXABI_TARGET_TRIPLE}")
 append_if(LIBCXXABI_COMPILE_FLAGS LIBCXXABI_GCC_TOOLCHAIN
          "-gcc-toolchain ${LIBCXXABI_GCC_TOOLCHAIN}")
 append_if(LIBCXXABI_COMPILE_FLAGS LIBCXXABI_SYSROOT