[Beignet] [PATCH] Append linker flags instead of overriding

[Steven Newbury]

When user LDFLAGS are set in the environment they shouldn't be
overridden.

Signed-off-by: Steven Newbury <steve at snewbury.org.uk>

---

--- backend/CMakeLists.txt.orig 2013-04-21 09:24:56.776171382 +0100
+++ backend/CMakeLists.txt      2013-04-21 09:26:52.083534324 +0100
@@ -49,7 +49,7 @@
   set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${GBE_DEBUG_MEMORY_FLAG}")
   set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${GBE_COMPILE_UTESTS_FLAG}")
   set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wl,-E")
-  set (CMAKE_SHARED_LINKER_FLAGS "-Wl,--no-undefined ${LLVM_LFLAGS}")
+  set (CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--no-undefined ${LLVM_LFLAGS}")
   set (CMAKE_CXX_FLAGS_DEBUG          "-g -DGBE_DEBUG=1")
   set (CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g -DGBE_DEBUG=1")
   set (CMAKE_CXX_FLAGS_MINSIZEREL     "-Os -DNDEBUG -DGBE_DEBUG=0")