libffi: Update to version 3.4.2

libffi: Update to version 3.4.2

- Update from 3.3 to 3.4.2
- Update rootfile - No dependency issues due to so bump
- Changelog
   3.4.2 Jun-28-21
     Add static trampoline support for Linux on x86_64 and ARM64.
     Add support for Alibaba's CSKY architecture.
     Add support for Kalray's KVX architecture.
     Add support for Intel Control-flow Enforcement Technology (CET).
     Add support for ARM Pointer Authentication (PA).
     Fix 32-bit PPC regression.
     Fix MIPS soft-float problem.
     Enable tmpdir override with the $LIBFFI_TMPDIR environment variable.
     Enable compatibility with MSVC runtime stack checking.
     Reject float and small integer argument in ffi_prep_cif_var().
       Callers must promote these types themselves.
   3.3 Nov-23-19
     Add RISC-V support.
     New API in support of GO closures.
     Add IEEE754 binary128 long double support for 64-bit Power
     Default to Microsoft's 64-bit long double ABI with Visual C++.
     GNU compiler uses 80 bits (128 in memory) FFI_GNUW64 ABI.
     Add Windows on ARM64 (WOA) support.
     Add Windows 32-bit ARM support.
     Raw java (gcj) API deprecated.
     Add pre-built PDF documentation to source distribution.
     Many new test cases and bug fixes.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>