Handle ADD/SUB relocations

This adds support for ADD and SUB relocations as seen on RISC-V.

Signed-off-by: Andreas Schwab <schwab@suse.de>
diff --git a/backends/sparc_symbol.c b/backends/sparc_symbol.c
index ec11dc9..e8ee391 100644
--- a/backends/sparc_symbol.c
+++ b/backends/sparc_symbol.c
@@ -39,7 +39,8 @@
 
 /* Check for the simple reloc types.  */
 Elf_Type
-sparc_reloc_simple_type (Ebl *ebl __attribute__ ((unused)), int type)
+sparc_reloc_simple_type (Ebl *ebl __attribute__ ((unused)), int type,
+			 int *addsub __attribute__ ((unused)))
 {
   switch (type)
     {