TCP input: add missing CMake dependency on Lz4

This seemed to mostly work because libfds depends on Lz4 and so we would mostly
find Lz4.h in the default system include path on Linux.
On FreeBSD though, Lz4.h is in a path that is not a part of the includes that
CMake would use by default, which revealed this issue.

Author: sedmicha

CMakeModules/FindLibLz4.cmake

@@ -0,0 +1,53 @@
+#  LIBLZ4_FOUND - System has LZ4
+#  LIBLZ4_INCLUDE_DIRS - The LZ4 include directories
+#  LIBLZ4_LIBRARIES - The libraries needed to use LZ4
+
+find_path(
+    LZ4_INCLUDE_DIR lz4.h
+    PATH_SUFFIXES include
+)
+
+find_library(
+    LZ4_LIBRARY
+    NAMES lz4 liblz4
+    PATH_SUFFIXES lib lib64
+)
+
+set(LZ4_HEADER_FILE "${LZ4_INCLUDE_DIR}/lz4.h")
+if (LZ4_INCLUDE_DIR AND EXISTS ${LZ4_HEADER_FILE})
+    # Try to extract library version from the header file
+    file(STRINGS ${LZ4_HEADER_FILE} lz4_major_define
+        REGEX "^#define[\t ]+LZ4_VERSION_MAJOR[\t ]+[0-9]+"
+        LIMIT_COUNT 1
+    )
+    file(STRINGS ${LZ4_HEADER_FILE} lz4_minor_define
+        REGEX "^#define[\t ]+LZ4_VERSION_MINOR[\t ]+[0-9]+"
+        LIMIT_COUNT 1
+    )
+    file(STRINGS ${LZ4_HEADER_FILE} lz4_release_define
+        REGEX "^#define[\t ]+LZ4_VERSION_RELEASE[\t ]+[0-9]+"
+        LIMIT_COUNT 1
+    )
+
+    string(REGEX REPLACE "^#define[\t ]+LZ4_VERSION_MAJOR[\t ]+([0-9]+).*" "\\1"
+        lz4_major_num ${lz4_major_define})
+    string(REGEX REPLACE "^#define[\t ]+LZ4_VERSION_MINOR[\t ]+([0-9]+).*" "\\1"
+        lz4_minor_num ${lz4_minor_define})
+    string(REGEX REPLACE "^#define[\t ]+LZ4_VERSION_RELEASE[\t ]+([0-9]+).*" "\\1"
+        lz4_release_num ${lz4_release_define})
+
+    set(LZ4_VERSION_STRING "${lz4_major_num}.${lz4_minor_num}.${lz4_release_num}")
+endif()
+unset(LZ4_HEADER_FILE)
+
+# Handle the REQUIRED arguments and set LIBLZ4_FOUND to TRUE if all listed
+# variables are TRUE
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(LibLz4
+    REQUIRED_VARS LZ4_LIBRARY LZ4_INCLUDE_DIR
+    VERSION_VAR LZ4_VERSION_STRING
+)
+
+set(LIBLZ4_LIBRARIES ${LZ4_LIBRARY})
+set(LIBLZ4_INCLUDE_DIRS ${LZ4_INCLUDE_DIR})
+mark_as_advanced(LZ4_INCLUDE_DIR LZ4_LIBRARY)

src/plugins/input/tcp/CMakeLists.txt

@@ -15,6 +15,10 @@ add_library(tcp-input MODULE
     src/IpxPlugin.cpp
 )
 
+find_package(LibLz4 REQUIRED)
+include_directories(${LIBLZ4_INCLUDE_DIRS})
+target_link_libraries(tcp-input ${LIBLZ4_LIBRARIES})
+
 if (CMAKE_HOST_SYSTEM_NAME STREQUAL "FreeBSD" OR CMAKE_HOST_SYSTEM_NAME STREQUAL "OpenBSD")
     find_package(LibEpollShim REQUIRED)
     include_directories(