cmd/link: always use symbol-targeted relocations on Mach-O
In Mach-O object files, there are two kinds of relocations:
"external" relocation, which targets a symbol, and "non-external"
relocation, which targets a section. For targeting symbols not in
the current object, we must use symbol-targeted relocations. For
targeting symbols defined in the current object, for some
relocation types, both kinds can be used. We currently use
section-targeted relocations for R_ADDR targeting locally defined
symbols.
Modern Apple toolchain seems to prefer symbol-targeted relocations.
Also, Apple's new linker, ld-prime, seems to not handle section-
targeted relocations well in some cases. So this CL switches to
always generate symbol-targeted relocations. This also simplifies
the code.
One exception is that DWARF tools seem to handle only section-
targeted relocations. So generate those in DWARF sections.
This CL supersedes CL 502616.
Fixes #60694.
For #61229.
Change-Id: I3b74df64f21114635061bcd89114392b3a2d588b
Reviewed-on: https://go-review.googlesource.com/c/go/+/503935 Reviewed-by: Than McIntosh <thanm@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>