[Bug libgcc/119396] libgcc: Shared objects are being built for target that doesn't support shared libs

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119396

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>From libgcc/Makefile.in:
```
enable_shared = @enable_shared@
...
# Only handle shared libraries if both:
#   - the user requested them
#   - we know how to build them
ifeq ($(SHLIB_LINK),)
  enable_shared := no
endif

ifeq ($(enable_shared),yes)
  iterator = $(patsubst %,$(srcdir)/shared-object.mk,$(iter-items))

  install-shared = install-shared

  ifneq ($(LIBUNWIND),)
    install-libunwind = install-libunwind
  endif
endif
...
ifeq ($(enable_shared),yes)
lib2funcs-s-o = $(patsubst %,%_s$(objext),$(lib2funcs))
$(lib2funcs-s-o): %_s$(objext): $(srcdir)/libgcc2.c
        $(gcc_s_compile) -DL$* -c $<
libgcc-s-objects += $(lib2funcs-s-o)
endif

```


enable_shared defaults to yes in configure.ac.

So now how is SHLIB_LINK defined.
SHLIB_LINK is defined in the following:
config/i386/t-slibgcc-cygming
config/rs6000/t-slibgcc-aix
config/t-slibgcc
config/t-slibgcc-darwin
config/t-slibgcc-vms

But I don't see any of those being set in tmake_file in config.host for avr.
Maybe I missed something