this sucks, in .c files they use "lz4" prefix, but in cmake no prefix

and should really just use pkgconfig

and it's iconsistent as well!

--- mysql-5.7.16/cmake/lz4.cmake~	2016-09-28 20:02:44.000000000 +0300
+++ mysql-5.7.16/cmake/lz4.cmake	2016-12-12 11:37:18.923456466 +0200
@@ -17,7 +17,7 @@
 # bundled is the default
 
 MACRO (FIND_SYSTEM_LZ4)
-  FIND_PATH(PATH_TO_LZ4 NAMES lz4frame.h)
+  FIND_PATH(PATH_TO_LZ4 NAMES lz4/lz4frame.h)
   FIND_LIBRARY(LZ4_SYSTEM_LIBRARY NAMES lz4)
   IF (PATH_TO_LZ4 AND LZ4_SYSTEM_LIBRARY)
     SET(SYSTEM_LZ4_FOUND 1)
--- mysql-5.7.16/storage/innobase/os/os0file.cc~	2016-09-28 20:02:44.000000000 +0300
+++ mysql-5.7.16/storage/innobase/os/os0file.cc	2016-12-12 12:12:43.810635067 +0200
@@ -70,7 +70,7 @@
 # include <linux/falloc.h>
 #endif /* HAVE_FALLOC_PUNCH_HOLE_AND_KEEP_SIZE */
 
-#include <lz4.h>
+#include <lz4/lz4.h>
 #include <zlib.h>
 
 #ifdef UNIV_DEBUG
@@ -8435,7 +8435,7 @@
 #include "fil0fil.h"
 #include "os0file.h"
 
-#include <lz4.h>
+#include <lz4/lz4.h>
 #include <zlib.h>
 
 #include <my_aes.h>
--- mysql-5.7.16/client/dump/compression_lz4_writer.h~	2016-09-28 20:02:44.000000000 +0300
+++ mysql-5.7.16/client/dump/compression_lz4_writer.h	2016-12-12 12:17:53.912464632 +0200
@@ -21,7 +21,7 @@
 #include "i_output_writer.h"
 #include "abstract_output_writer_wrapper.h"
 #include "i_callable.h"
-#include <lz4frame.h>
+#include <lz4/lz4frame.h>
 #include "base/mutex.h"
 #include <string.h>
 
--- mysql-5.7.17/rapid/plugin/group_replication/libmysqlgcs/src/bindings/xcom/gcs_message_stage_lz4.cc~	2016-11-28 15:32:52.000000000 +0200
+++ mysql-5.7.17/rapid/plugin/group_replication/libmysqlgcs/src/bindings/xcom/gcs_message_stage_lz4.cc	2016-12-14 16:39:53.124878289 +0200
@@ -15,7 +15,7 @@
 
 #include "gcs_internal_message.h"
 #include "gcs_message_stage_lz4.h"
-#include <lz4.h>
+#include <lz4/lz4.h>
 #include <mysql/gcs/xplatform/byteorder.h>
 #include "gcs_logging.h"
 #include <string.h>