[committed] MIPS/BFD: Remove EI_ABIVERSION 5 allocation for PT_GNU_STACK support

[Maciej W. Rozycki]

Revert commit 17733f5be961 ("Increment the ABIVERSION to 5 for MIPS
objects with non-executable stacks.") and remove EI_ABIVERSION 5
allocation for PT_GNU_STACK support, which has not made it to glibc
and will be reassigned.

	bfd/
	* bfd/elfxx-mips.c (_bfd_mips_post_process_headers): Revert
	2016-02-23 change and remove EI_ABIVERSION 5 support.
---
 Applied to master, as per the discussion around 
<https://www.sourceware.org/ml/libc-alpha/2016-12/msg00857.html>, and 
backported to 2.28 and 2.27 branches.

  Maciej

diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c
index d649676..486607c 100644
--- a/bfd/elfxx-mips.c
+++ b/bfd/elfxx-mips.c
@@ -16358,9 +16358,6 @@ _bfd_mips_post_process_headers (bfd *abfd, struct bfd_link_info *link_info)
   if (mips_elf_tdata (abfd)->abiflags.fp_abi == Val_GNU_MIPS_ABI_FP_64
       || mips_elf_tdata (abfd)->abiflags.fp_abi == Val_GNU_MIPS_ABI_FP_64A)
     i_ehdrp->e_ident[EI_ABIVERSION] = 3;
-
-  if (elf_stack_flags (abfd) && !(elf_stack_flags (abfd) & PF_X))
-    i_ehdrp->e_ident[EI_ABIVERSION] = 5;
 }
 
 int