libffi: Update to version 3.4.6

libffi: Update to version 3.4.6

- Update from version 3.4.4 to 3.4.6
- Update of rootfile
- Changelog
    3.4.6
	Fix long double regression on mips64 and alpha.
    3.4.5
	Add support for wasm32.
	Add support for aarch64 branch target identification (bti).
	Add support for ARCv3: ARC32 & ARC64.
	Add support for HPPA64, and many HPPA fixes.
	Add support for Haikuos on PowerPC.
	Fixes for AIX, loongson, MIPS, power, sparc64, and x86 Darwin.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>