libffi: Update to version 3.4.8

libffi: Update to version 3.4.8

- Update from version 3.4.7 to 3.4.8
- Update of rootfile not required
- Changelog
    3.4.8
	    aarch64: add PAC to GNU Notes by @billatarm in #882
	    MIPS: Dont import asm/sgidefs.h on linux by @fossdd in #885
	    Update the Simple Example from the Docs to fix a compile error by
	     @Nikitf777 in #886
	    Fix bugs in the x86-64 and x32 target (#887) by @mikulas-patocka in #889
	    Add the "ABI_ATTR" attribute to called functions (#891) by @mikulas-patocka
	     in #892
	    powerpc: Add static trampoline support (#894) by @peter-bergner in #895
	    testsuite: add two tests to Makefile.am by @thesamesam in #893

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