[RFC PATCH] elf: Fix link error missing Unwind_Backtrace symbol

[Stafford Horne]

---
For some reason build many is failing with missing Unwind_Backtrace symbol
when linking tst-unwind-ctor-lib.so.

    or1k-glibc-linux-gnu-gcc   -shared -static-libgcc  -Wl,-dynamic-linker=/lib/ld-linux-or1k.so.1 -Wl,-z,defs -B/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/csu/  -Wl,-z,combreloc -Wl,-z,relro -Wl,--hash-style=both  -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/math -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/elf -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/dlfcn -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/nss -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/nis -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/rt -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/resolv -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/mathvec -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/support -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/crypt -L/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/nptl -Wl,-rpath-link=/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/math:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/elf:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/dlfcn:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/nss:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/nis:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/rt:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/resolv:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/mathvec:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/support:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/crypt:/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/nptl -o /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/elf/tst-unwind-ctor-lib.so -T /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/shlib.lds /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/csu/abi-note.o /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/elf/tst-unwind-ctor-lib.os  -Wl,--start-group /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/libc.so /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/libc_nonshared.a -Wl,--as-needed /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/elf/ld.so -Wl,--no-as-needed -Wl,--end-group
    /home/shorne/work/gnu-toolchain/build-many/install/compilers/or1k-linux-gnu/lib/gcc/or1k-glibc-linux-gnu/12.0.0/../../../../or1k-glibc-linux-gnu/bin/ld: /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/elf/tst-unwind-ctor-lib.os: in function `do_unwind':
    /home/shorne/work/gnu-toolchain/glibc/elf/tst-unwind-ctor-lib.c:36: undefined reference to `_Unwind_Backtrace'

Adding the -lgcc_s fixes this.  I am not sure why this is just showing up now,
I just re-bootstrapped my build-many compilers and this error started showing
up.  I notice its not happending on the test results mailing list.  Perhaps
someone has an idea?

This patch fixes it and the check phase passes.

 elf/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/elf/Makefile b/elf/Makefile
index b86d116be9..5bf9a3eb64 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -2011,6 +2011,7 @@ $(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so
 $(objpfx)tst-big-note-lib.so: $(objpfx)tst-big-note-lib.o
 	$(LINK.o) -shared -o $@ $(LDFLAGS.so) $<
 
+LDLIBS-tst-unwind-ctor-lib.so = -lgcc_s
 $(objpfx)tst-unwind-ctor: $(objpfx)tst-unwind-ctor-lib.so
 
 CFLAGS-tst-unwind-main.c += -funwind-tables -DUSE_PTHREADS=0
-- 
2.31.1