Merge pull request #1282 from rdb/master

Fix error when custom CMAKE_C_FLAGS is specified

CMakeLists.txt

@@ -178,7 +178,7 @@ ENDIF( UNIX )
 IF ((CMAKE_C_COMPILER_ID MATCHES "GNU") AND NOT CMAKE_COMPILER_IS_MINGW)
   # hide all not-exported symbols
   SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -fvisibility=hidden -fPIC -Wall -std=c++0x")
-  SET(CMAKE_C_FLAGS ${CMAKE_C_FLAGS} -fPIC)
+  SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC")
   SET(LIBSTDC++_LIBRARIES -lstdc++)
 ELSEIF(MSVC)
   # enable multi-core compilation with MSVC