Bump medialibrary: migrate to meson

In order to get the latest medialibrary updates, a migration to meson was mandatory.

To be in compliance with the dependency requirement of the following we decided to revert:

53bfda26.

The medialibrary needs a sqlite3 version of >= 3.33.0 which isn't present in the oldest versions of iOS we support(e.g. iOS 9.x).

The buildscript now uses meson in order to build the medialibrary.

Additionally, it generates the necessary cross compilation files under $ProjectDIR/buildscript/crossfiles.

This is an example of a generated 'crossfile' for iPhoneSimulator x86_64.

cat VLCMediaLibraryKit/buildsystem/crossfiles/x86_64-Simulator.crossfile

# This file is autogenerated by buildVLCMediaLibraryKit.sh

[constants]
common_flags = ['-arch', 'x86_64', '-miphoneos-version-min=9.0', '-isysroot', '/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator14.5.sdk']

[binaries]
c = 'clang'
cpp = 'clang++'
objc = 'clang'
objcpp = 'clang++'
ar = 'ar'
strip = 'strip'
pkgconfig = 'pkg-config'

[built-in options]
c_args = common_flags
cpp_args = common_flags
c_link_args = common_flags
cpp_link_args = common_flags
objc_args = common_flags
objcpp_args = common_flags

[host_machine]
system = 'darwin'
cpu_family = 'x86_64'
endian = 'little'
cpu = 'x86_64'

cc: @chouquette