Disable USE_PT_GNU_EH_FRAME frame unwinder support for old OS versions,
fixing compilation errors:
.../libgcc/unwind-dw2-fde-dip.c:75:21: error: unknown type name 'Elf_Phdr'
75 | # define ElfW(type) Elf_##type
| ^~~~
.../libgcc/unwind-dw2-fde-dip.c:132:9: note: in expansion of macro 'ElfW'
132 | const ElfW(Phdr) *p_eh_frame_hdr;
| ^~~~
.../libgcc/unwind-dw2-fde-dip.c:75:21: error: unknown type name 'Elf_Phdr'
75 | # define ElfW(type) Elf_##type
| ^~~~
.../libgcc/unwind-dw2-fde-dip.c:133:9: note: in expansion of macro 'ElfW'
133 | const ElfW(Phdr) *p_dynamic;
| ^~~~
.../libgcc/unwind-dw2-fde-dip.c:165:37: warning: 'struct dl_phdr_info' declared inside parameter list will not be visible outside of this definition or declaration
165 | _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
| ^~~~~~~~~~~~
[...]
and producing a working cross-compiler at least with VAX/NetBSD 1.6.2.
libgcc/
* unwind-dw2-fde-dip.c [__OpenBSD__ || __NetBSD__]
(USE_PT_GNU_EH_FRAME): Do not define if !TARGET_DL_ITERATE_PHDR.
f50c417a03