PR27228, .reloc wrong symbol emitted for undefined local symbol

Local symbols are of course supposed to be defined by their object
file, but in other cases a local symbol is promoted to global by gas
if undefined and referenced.  This patch stops gas wrongly replacing a
local undefined symbol with the undefined section symbol, resulting in
a .reloc undefined local symbol being emitted as global.

	PR 27228
	* write.c (resolve_reloc_expr_symbols): Don't assume local symbol
	is defined.

(cherry picked from commit 68fcee4)

Author: amodra

gas/ChangeLog

@@ -1,3 +1,9 @@
+2021-01-24  Alan Modra  <[email protected]>
+
+	PR 27228
+	* write.c (resolve_reloc_expr_symbols): Don't assume local symbol
+	is defined.
+
 2021-01-21  Alan Modra  <[email protected]>
 
 	PR 27221

gas/write.c

@@ -737,7 +737,9 @@ resolve_reloc_expr_symbols (void)
 		 prevent the offset from overflowing the relocated field,
 	         unless it has enough bits to cover the whole address
 	         space.  */
-	      if (S_IS_LOCAL (sym) && !symbol_section_p (sym)
+	      if (S_IS_LOCAL (sym)
+		  && S_IS_DEFINED (sym)
+		  && !symbol_section_p (sym)
 		  && (sec->use_rela_p
 		      || (howto->partial_inplace
 			  && (!howto->pc_relative