fix warning in common.h reported by clang-tidy

lib/include/srslte/common/common.h

@@ -122,7 +122,9 @@ public:
     byte_buffer_t():N_bytes(0)
     {
       bzero(buffer, SRSLTE_MAX_BUFFER_SIZE_BYTES);
+#ifdef ENABLE_TIMESTAMP
       timestamp_is_set = false;
+#endif
       msg  = &buffer[SRSLTE_BUFFER_HEADER_OFFSET];
       next = NULL; 
 #ifdef SRSLTE_BUFFER_POOL_LOG_ENABLED
@@ -149,7 +151,9 @@ public:
     {
       msg       = &buffer[SRSLTE_BUFFER_HEADER_OFFSET];
       N_bytes   = 0;
+#ifdef ENABLE_TIMESTAMP
       timestamp_is_set = false;
+#endif
     }
     uint32_t get_headroom()
     {
@@ -183,8 +187,10 @@ public:
 
 private:
 
+#ifdef ENABLE_TIMESTAMP
     struct timeval timestamp[3];
     bool           timestamp_is_set; 
+#endif
     byte_buffer_t *next;
 };
 
@@ -199,6 +205,9 @@ struct bit_buffer_t{
     bit_buffer_t():N_bits(0)
     {
       msg = &buffer[SRSLTE_BUFFER_HEADER_OFFSET];
+#ifdef ENABLE_TIMESTAMP
+      timestamp_is_set = false;
+#endif
     }
     bit_buffer_t(const bit_buffer_t& buf){
       N_bits = buf.N_bits;
@@ -216,7 +225,9 @@ struct bit_buffer_t{
     {
       msg       = &buffer[SRSLTE_BUFFER_HEADER_OFFSET];
       N_bits    = 0;
+#ifdef ENABLE_TIMESTAMP
       timestamp_is_set = false;
+#endif
     }
     uint32_t get_headroom()
     {
@@ -242,9 +253,10 @@ struct bit_buffer_t{
     }
 
 private:
+#ifdef ENABLE_TIMESTAMP
     struct timeval timestamp[3];
     bool           timestamp_is_set; 
-
+#endif
 };
 
 } // namespace srslte