Get rid of clang warnings for UC_INLINE

include/ucore/mbuf.h

@@ -4,10 +4,16 @@
 #include <stddef.h>
 #include "tailq.h"
 
+#ifndef UC_INLINE
 #ifdef __GNUC__
-#   define UC_INLINE inline __attribute__((always_inline))
+#  ifdef __clang__
+#    define UC_INLINE inline __attribute__((always_inline))
+#  else
+#    define UC_INLINE inline __attribute__((always_inline,flatten))
+#  endif
 #else
-#   define UC_INLINE inline
+#  define UC_INLINE inline
+#endif
 #endif
 
 enum UC_MBUF_FLAGS {

include/ucore/pack.h

@@ -2,10 +2,17 @@
 #define UC_PACK_H_
 
 #include <stdint.h>
+
+#ifndef UC_INLINE
 #ifdef __GNUC__
-#   define UC_INLINE inline __attribute__((always_inline))
+#  ifdef __clang__
+#    define UC_INLINE inline __attribute__((always_inline))
+#  else
+#    define UC_INLINE inline __attribute__((always_inline,flatten))
+#  endif
 #else
-#   define UC_INLINE inline
+#  define UC_INLINE inline
+#endif
 #endif
 
 /** Functions for serializing/de-serializing integers to and from

include/ucore/tailq.h

@@ -1,10 +1,16 @@
 #ifndef UC_TAILQ_H_
 #define UC_TAILQ_H_
 
+#ifndef UC_INLINE
 #ifdef __GNUC__
-#define UC_INLINE inline __attribute__((always_inline,flatten))
+#  ifdef __clang__
+#    define UC_INLINE inline __attribute__((always_inline))
+#  else
+#    define UC_INLINE inline __attribute__((always_inline,flatten))
+#  endif
 #else
-#define UC_INLINE inline
+#  define UC_INLINE inline
+#endif
 #endif
 /**
  * Doubly Linked List.