[Bug libffi/108682] libffi needs to merge upstream to get LoongArch support

["xry111 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108682

--- Comment #2 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
I applied the LoongArch port patch (upstream PR 678, config.guess and
config.sub changes stripped and Makefile.am conflict resolved manually) and use
autogen.sh to regenerate the build system.  But libgo build still fails with:

libtool: compile:  /home/xry111/git-repos/gcc-build/./gcc/gccgo
-B/home/xry111/git-repos/gcc-build/./gcc/
-B/home/xry111/gcc-trunk/loongarch64-unknown-linux-gnu/bin/
-B/home/xry111/gcc-trunk/loongarch64-unknown-linux-gnu/lib/ -isystem
/home/xry111/gcc-trunk/loongarch64-unknown-linux-gnu/include -isystem
/home/xry111/gcc-trunk/loongarch64-unknown-linux-gnu/sys-include -O2 -g -I . -c
-fgo-pkgpath=internal/goarch ../../../gcc/libgo/go/internal/goarch/goarch.go
zgoarch.go  -fPIC -o internal/.libs/goarch.o
zgoarch.go:7:14: error: expected ‘;’ or ‘)’ or newline
    7 |   _BigEndian =
      |              ^
zgoarch.go:7:3: error: reference to undefined name ‘_BigEndian’
    7 |   _BigEndian =
      |   ^
../../../gcc/libgo/go/internal/goarch/goarch.go:18:19: error: reference to
undefined name ‘_BigEndian’
   18 | const BigEndian = _BigEndian
      |                   ^
../../../gcc/libgo/go/internal/goarch/goarch.go:21:29: error: reference to
undefined name ‘_DefaultPhysPageSize’
   21 | const DefaultPhysPageSize = _DefaultPhysPageSize
      |                             ^
../../../gcc/libgo/go/internal/goarch/goarch.go:25:19: error: reference to
undefined name ‘_PCQuantum’
   25 | const PCQuantum = _PCQuantum
      |                   ^
../../../gcc/libgo/go/internal/goarch/goarch.go:28:20: error: reference to
undefined name ‘_Int64Align’
   28 | const Int64Align = _Int64Align
      |                    ^
../../../gcc/libgo/go/internal/goarch/goarch.go:35:22: error: reference to
undefined name ‘_MinFrameSize’
   35 | const MinFrameSize = _MinFrameSize
      |                      ^
../../../gcc/libgo/go/internal/goarch/goarch.go:39:20: error: reference to
undefined name ‘_StackAlign’
   39 | const StackAlign = _StackAlign
      |                    ^