[Bug go/66870] split stack issues on ppc64le and ppc64

["boger at us dot ibm.com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66870

--- Comment #17 from boger at us dot ibm.com ---
Created attachment 36132
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36132&action=edit
Configure gold linker with split stack if available

Attaching my patch to detect for split stack support within the gold linker
that is available by the gcc build, and then use it with gccgo compiles.  Here
are the steps:
- When configuring gcc, check for split stack support in the gold linker either
identified as the linker to use in the gcc build or found in the path at build
time.  This check currently only works on ppc64le; I couldn't get it to fail on
ppc64 even with older (2.24) gold linkers.  Not sure what might be wanted for
other targets.  If the support is there then HAVE_LD_GOLD_SUPPORTS_SPLIT_STACK
is defined.
- Modify the check in libgo configure to detect that the gold linker used with
the gccgo that was just built supports split stack, defining
LINKER_SUPPORTS_SPLIT_STACK if it is.
- Add -fuse-ld=gold to the linker spec if HAVE_LD_GOLD_SUPPORTS_SPLIT_STACK is
defined (not for m32).
- Define TARGET_CAN_SPLIT_STACK for Power targets if the glibc level is
correct.  This is needed by go/gospec.c to enable the -fsplit-stack option when
linking.  

Comments?