Update meson build system

NOTE: This commit only tested on Linux (Ubuntu 18.04). Windows
build may not work as expected.

* Use meson >= 0.47.0 cause we use install_man function
* Add three helper Python script:
  * CopyFile.py: To copy file
  * CreateSymlink.py: To make symlink (both Windows and Unix)
  * GetZstdLibraryVersion.py: Parse lib/zstd.h to get zstd version
  These help emulating equivalent functions in CMake and Makefile.
* Use subdir from meson to split meson.build
  * Add contrib build
  * Fix other build
* Add new build options
  * build_programs: Enable programs build
  * build_contrib: Enable contrib build
  * build_tests: Enable tests build
  * use_static_runtime: Link to static run-time libraries on MSVC
  * zlib_support: Enable zlib support
  * lzma_support: Enable lzma support

contrib/meson/GetZstdLibraryVersion.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+# #############################################################################
+# Copyright (c) 2018-present    lzutao <taolzu(at)gmail.com>
+# All rights reserved.
+#
+# This source code is licensed under both the BSD-style license (found in the
+# LICENSE file in the root directory of this source tree) and the GPLv2 (found
+# in the COPYING file in the root directory of this source tree).
+# #############################################################################
+import re
+import sys
+
+
+def usage():
+    print('usage: python3 GetZstdLibraryVersion.py <path/to/zstd.h>')
+    sys.exit(1)
+
+
+def find_version(filepath):
+    version_file_data = None
+    with open(filepath) as fd:
+        version_file_data = fd.read()
+
+    patterns = r"""#\s*define\s+ZSTD_VERSION_MAJOR\s+([0-9]+)
+#\s*define\s+ZSTD_VERSION_MINOR\s+([0-9]+)
+#\s*define\s+ZSTD_VERSION_RELEASE\s+([0-9]+)
+"""
+    regex = re.compile(patterns, re.MULTILINE)
+    version_match = regex.search(version_file_data)
+    if version_match:
+        return version_match.groups()
+    raise RuntimeError("Unable to find version string.")
+
+
+def main():
+    if len(sys.argv) < 2:
+        usage()
+
+    filepath = sys.argv[1]
+    version_tup = find_version(filepath)
+    print('.'.join(version_tup))
+
+
+if __name__ == '__main__':
+    main()