[cmake] Drop the support of CMake 2.x.
* CMakeLists.txt: Require CMake 3.0 (released on 2014) or newer.
The issue #1059 reports the difficulty to support both of
CMake 2.x and newer one by single CMakeLists.txt without
the inflation of cmake_policy() workarounds.
For better maintainability, the support of CMake 2.x is
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 85babdd..9e66cde 100644
@@ -106,10 +106,9 @@
# (this is compatible with the same CMake variables in zlib's CMake
-# FreeType explicitly marks the API to be exported and relies on the compiler
-# to hide all other symbols. CMake supports a C_VISBILITY_PRESET property
-# starting with 2.8.12.
+# To minimize the number of cmake_policy() workarounds,
+# CMake >= 3 is requested.
if (NOT CMAKE_VERSION VERSION_LESS 3.3)
# Allow symbol visibility settings also on static libraries. CMake < 3.3