toolchain/54509: clang build fails for aarch64

[rjs%fdy2.co.uk@localhost]

>Number:         54509
>Category:       toolchain
>Synopsis:       clang build of NetBSD for aarch64 fails
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Aug 29 22:10:00 +0000 2019
>Originator:     Robert Swindells
>Release:        NetBSD 9.99.10
>Organization:
	NetBSD
>Environment:
System: NetBSD ren.fdy2.co.uk 9.99.4 NetBSD 9.99.4 (REN) #16: Wed Aug 7 22:21:07 BST 2019 rjs%ren.fdy2.co.uk@localhost:/u1/src/sys/arch/amd64/compile/REN amd64
Architecture: x86_64
Machine: amd64
>Description:
Build for aarch64 using clang fails with this error:

#     build  libc/libc.so.12.213
rm -f libc.so.12.213
/u8/build/aarch64l-tools/bin/aarch64--netbsd-clang -nodefaultlibs -shared -Wl,-s
oname,libc.so.12  -Wl,--warn-shared-textrel -Wl,-Map=libc.so.12.map -Wl,-z,initf
irst -Wl,-z,defs   --sysroot=/var/obj/aarch64l -Wl,--fatal-warnings -Wl,--warn-s
hared-textrel  -o libc.so.12.213.tmp  -Wl,-rpath,/lib  -L=/lib -Wl,-x  -Wl,--who
le-archive libc_pic.a  -Wl,--no-whole-archive
/u8/build/aarch64l-tools/bin/aarch64--netbsd-ld: libc_pic.a(fixxfdi.pico): in
function `__fixxfdi':
fixxfdi.c:(.text+0x40): undefined reference to `__gttf2'
aarch64--netbsd-clang: error: linker command failed with exit code 1 (use -v to
see invocation)

>How-To-Repeat:
With these variables set:

MKLLVM=yes
HAVE_LLVM=yes
MKGCC=no

# ./build.sh -m evbarm64-el distribution

>Fix:

>Unformatted: