[committed 3/5] PR ld/20828: Work around RISC-V failures

[Maciej W. Rozycki]

Complement commit 81ff47b3a546 ("PR ld/20828: Fix linker script symbols
wrongly forced local with section GC") and add `.plt' to the list of 
output sections created, fixing:

FAIL: PR ld/20828 dynamic symbols with section GC (auxiliary shared library)
FAIL: PR ld/20828 dynamic symbols with section GC (plain)
FAIL: PR ld/20828 dynamic symbols with section GC (version script)

failures with `riscv32-elf', `riscv32-linux', `riscv64-elf' and 
`riscv64-linux' targets caused by LD crashing in the absence of such a 
section.

	ld/
	PR ld/20828
	* testsuite/ld-elf/pr20828.ld: Add `.plt'.
---
 Committed as obvious and backported to 2.28.

  Maciej

binutils-bfd-elf-link-assignment-forced-local-test-riscvxx-elf.diff
Index: binutils/ld/testsuite/ld-elf/pr20828.ld
===================================================================
--- binutils.orig/ld/testsuite/ld-elf/pr20828.ld	2017-01-18 23:39:05.000000000 +0000
+++ binutils/ld/testsuite/ld-elf/pr20828.ld	2017-01-20 13:52:21.319633176 +0000
@@ -13,6 +13,7 @@ SECTIONS
   .shstrtab : { *(.shstrtab) }
   .symtab : { *(.symtab) }
   .strtab : { *(.strtab) }
+  .plt : { *(.plt) }
   .got.plt : { *(.got.plt) }
   .got : { *(.got) }
   /DISCARD/ : { *(*) }