Check for compiler flags not available with gcc < 4.

--- CMakeLists.txt.orig	Tue Dec 20 01:23:22 2011
+++ CMakeLists.txt	Sat Nov  2 11:38:51 2013
@@ -54,9 +54,14 @@ ELSE (WIN32)
     IF(HAVE_GCC_VISIBILITY)
       SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fvisibility=hidden")
     ENDIF(HAVE_GCC_VISIBILITY)
+    CHECK_C_COMPILER_FLAG(-Wold-style-definition HAVE_GCC_WOLDSTYLE)
+    IF(HAVE_GCC_WOLDSTYLE)
+      SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wold-style-definition")
+    ENDIF(HAVE_GCC_WOLDSTYLE)
   ENDIF(CMAKE_COMPILER_IS_GNUCC)
   SET(CMAKE_C_FLAGS
-      "${CMAKE_C_FLAGS} -std=c99 -pedantic -Wpointer-arith -Wno-format-y2k -Wstrict-prototypes -Wmissing-declarations -Wnested-externs -Wextra	-Wundef -Wwrite-strings -Wold-style-definition -Wredundant-decls -Wno-unused-parameter -Wno-sign-compare -Wmissing-prototypes")
+      "${CMAKE_C_FLAGS} -std=c99 -pedantic -Wpointer-arith -Wno-format-y2k -Wstrict-prototypes -Wmissing-declarations -Wnested-externs -Wextra -Wundef -Wwrite-strings -Wredundant-decls -Wno-unused-parameter -Wno-sign-compare -Wmissing-prototypes")
+  
 
   SET(CMAKE_C_FLAGS_DEBUG "-DDEBUG -g")
   SET(CMAKE_C_FLAGS_RELEASE "-DNDEBUG -O2 -Wuninitialized")