nios2: Add BFD support for GOT-relative DW_EH_PE_datarel encodings

There's already existing logic to handle this on other targets, so
this patch just makes nios2 use it.

2020-01-31  Sandra Loosemore  <sandra@codesourcery.com>

	bfd/
	* elf-eh-frame.c (_bfd_elf_write_section_eh_frame): DW_EH_PE_datarel
	encodings are relative to the GOT on nios2, too.

bfd/ChangeLog

@@ -1,3 +1,8 @@
+2020-01-31  Sandra Loosemore  <sandra@codesourcery.com>
+
+	* elf-eh-frame.c (_bfd_elf_write_section_eh_frame): DW_EH_PE_datarel
+	encodings are relative to the GOT on nios2, too.
+
 2020-01-31  Alan Modra  <amodra@gmail.com>
 
 	* Makefile.am (elf32-target.h, elf64-target.h): Don't use a temp

bfd/elf-eh-frame.c

@@ -2149,6 +2149,7 @@ _bfd_elf_write_section_eh_frame (bfd *abfd,
 			/* Fall thru */
 		      case bfd_arch_frv:
 		      case bfd_arch_i386:
+		      case bfd_arch_nios2:
 			BFD_ASSERT (htab->hgot != NULL
 				    && ((htab->hgot->root.type
 					 == bfd_link_hash_defined)