Weak defined function is turned into non-weak defined function by
"ld -r -flto" with GCC 5 due to a GCC 5 regression:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67548
Add "ld -r" tests for PR ld/15323 to make sure that any linker change
won't introduce linker regression for PR ld/15323.
* ld-plugin/lto.exp (lto_link_tests): Add a "ld -r" test for
PR ld/15323.
(lto_run_tests): Add a "ld -r" test for PR ld/15323.
bfd/
PR ld/15323
* elf32-i386.c (elf_i386_check_relocs): Set non_ir_ref if a
symbol is referenced by a non-shared object.
* elf64-x86-64.c (elf_x86_64_check_relocs): Likewise.
ld/testsuite/
PR ld/15323
* ld-plugin/lto.exp (lto_link_tests): Add pr15323a-r.o.
(lto_run_tests): Add a test for PR ld/15323.
* ld-plugin/pr15323.out: New file.
* ld-plugin/pr15323a.c: Likewise.
* ld-plugin/pr15323b.c: Likewise.
