Add missing CFLAGS -fPIC.

This entry was missing due revert of CMAKE_POSITION_INDEPENDENT_CODE
usage. Reported by @Sailsman63

CMakeLists.txt

@@ -177,7 +177,8 @@ ENDIF( UNIX )
 # Grouped compiler settings
 IF ((CMAKE_C_COMPILER_ID MATCHES "GNU") AND NOT CMAKE_COMPILER_IS_MINGW)
   # hide all not-exported symbols
-  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -fvisibility=hidden -fPIC -Wall -std=c++0x" )
+  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -fvisibility=hidden -fPIC -Wall -std=c++0x")
+  SET(CMAKE_C_FLAGS ${CMAKE_C_FLAGS} -fPIC)
   SET(LIBSTDC++_LIBRARIES -lstdc++)
 ELSEIF(MSVC)
   # enable multi-core compilation with MSVC