x86-64: Treat R_X86_64_PLT32 as R_X86_64_PC32

Starting from binutils commit bd7ab16b4537788ad53521c45469a1bdae84ad4a:
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=bd7ab16b4537788ad53521c45469a1bdae84ad4a
x86-64 assembler generates R_X86_64_PLT32, instead of R_X86_64_PC32, for
32-bit PC-relative branches.  Grub2 should treat R_X86_64_PLT32 as
R_X86_64_PC32.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

--- util/grub-mkimagexx.c
+++ util/grub-mkimagexx.c
@@ -841,6 +841,7 @@ SUFFIX (relocate_addresses) (Elf_Ehdr *e, Elf_Shdr *sections,
 		  break;
 
 		case R_X86_64_PC32:
+		case R_X86_64_PLT32:
 		  {
 		    grub_uint32_t *t32 = (grub_uint32_t *) target;
 		    *t32 = grub_host_to_target64 (grub_target_to_host32 (*t32)
diff --git a/util/grub-module-verifier.c b/util/grub-module-verifier.c
index 9179285..a79271f 100644
--- util/grub-module-verifier.c
+++ util/grub-module-verifier.c
@@ -19,6 +19,7 @@ struct grub_module_verifier_arch archs[] = {
       -1
     }, (int[]){
       R_X86_64_PC32,
+      R_X86_64_PLT32,
       -1
     }
   },