Attempt to fix libunwind build

git-svn-id: https://llvm.org/svn/llvm-project/libunwind/trunk@271466 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 53b114b..b7c2d63 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -105,9 +105,9 @@
                         VERSION       "1.0"
                         SOVERSION     "1")
 set_property(SOURCE ${LIBUNWIND_CXX_SOURCES}
-             APPEND_STRING PROPERTY COMPILE_FLAGS "${CMAKE_CXX_FLAGS} ${LIBUNWIND_CXX_FLAGS}")
+             APPEND_STRING PROPERTY COMPILE_FLAGS " ${CMAKE_CXX_FLAGS} ${LIBUNWIND_CXX_FLAGS}")
 set_property(SOURCE ${LIBUNWIND_C_SOURCES}
-             APPEND_STRING PROPERTY COMPILE_FLAGS "${CMAKE_C_FLAGS} ${LIBUNWIND_C_FLAGS}")
+             APPEND_STRING PROPERTY COMPILE_FLAGS " ${CMAKE_C_FLAGS} ${LIBUNWIND_C_FLAGS}")
 
 install(TARGETS unwind
         LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}