Bump minimum cmake version to 3.5 to avoid deprecation warning

Building msgpack gives currently gives the following warning:
"CMake Deprecation Warning at CMakeLists.txt:1 (CMAKE_MINIMUM_REQUIRED):
  Compatibility with CMake < 3.5 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions."

CMakeLists.txt

@@ -1,9 +1,4 @@
-CMAKE_MINIMUM_REQUIRED (VERSION 2.8.12)
-
-IF ((CMAKE_VERSION VERSION_GREATER 3.1) OR
-    (CMAKE_VERSION VERSION_EQUAL 3.1))
-    CMAKE_POLICY(SET CMP0054 NEW)
-ENDIF ()
+CMAKE_MINIMUM_REQUIRED (VERSION 3.5)
 
 OPTION (MSGPACK_BUILD_TESTS "Build msgpack tests." OFF)
 OPTION (MSGPACK_GEN_COVERAGE "Enable running gcov to get a test coverage report." OFF)
@@ -38,7 +33,7 @@ IF (BIGENDIAN)
     SET(MSGPACK_ENDIAN_LITTLE_BYTE 0)
 ELSE ()
     SET(MSGPACK_ENDIAN_BIG_BYTE 0)
-        SET(MSGPACK_ENDIAN_LITTLE_BYTE 1)
+    SET(MSGPACK_ENDIAN_LITTLE_BYTE 1)
 ENDIF ()
 
 CONFIGURE_FILE (

ci/build_cmake.sh

@@ -20,12 +20,13 @@ if [ "${ARCH}" == "32" ]
 then
     export BIT32="ON"
     export ARCH_FLAG="-m32"
+    ZLIB32="-DZLIB_LIBRARY=/usr/lib32/libz.a"
 else
     export BIT32="OFF"
     export ARCH_FLAG="-m64"
 fi
 
-cmake -DMSGPACK_BUILD_TESTS=ON -DMSGPACK_32BIT=${BIT32} -DBUILD_SHARED_LIBS=${SHARED} -DMSGPACK_CHAR_SIGN=${CHAR_SIGN} -DCMAKE_CXX_FLAGS="${ARCH_FLAG} ${CXXFLAGS} ${SAN}" -DCMAKE_C_FLAGS="${CFLAGS} ${SAN}" ..
+cmake -DMSGPACK_BUILD_TESTS=ON -DMSGPACK_32BIT=${BIT32} -DBUILD_SHARED_LIBS=${SHARED} -DMSGPACK_CHAR_SIGN=${CHAR_SIGN} -DCMAKE_CXX_FLAGS="${ARCH_FLAG} ${CXXFLAGS} ${SAN}" -DCMAKE_C_FLAGS="${CFLAGS} ${SAN}" ${ZLIB32} ..
 
 ret=$?
 if [ $ret -ne 0 ]

example/cmake/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 3.0)
+cmake_minimum_required (VERSION 3.5)
 project (example)
 
 if(EXAMPLE_MSGPACK_EMBEDDED)