Do not set STT_GNU_IFUNC to symbols .dynsym

We should not set STT_GNU_IFUNC to symbols in .dynsym because
from the other ELF module's point of view, it doens't matter
whether a symbol is IFUNC or not.

This is needed by Gentoo's sci-mathematics/nauty-2.6.7 package.

output_chunks.cc

@@ -968,7 +968,9 @@ void DynsymSection<E>::copy_buf(Context<E> &ctx) {
       *(ElfSym<E> *)(base + sym.get_dynsym_idx(ctx) * sizeof(ElfSym<E>));
 
     memset(&esym, 0, sizeof(esym));
-    esym.st_type = sym.get_type();
+    esym.st_type = sym.esym().st_type;
+    if (esym.st_type == STT_GNU_IFUNC)
+      esym.st_type = STT_FUNC;
     esym.st_size = sym.esym().st_size;
 
     if (sym.is_weak)

test/ifunc-export.sh

@@ -0,0 +1,37 @@
+#!/bin/bash
+set -e
+cd $(dirname $0)
+echo -n "Testing $(basename -s .sh $0) ... "
+t=$(pwd)/tmp/$(basename -s .sh $0)
+mkdir -p $t
+
+cat <<EOF | cc -c -fPIC -o $t/a.o -x assembler -
+.text
+real_foobar:
+  lea     .Lmsg(%rip), %rdi
+  xor     %rax, %rax
+  call    printf
+  xor     %rax, %rax
+  ret
+
+.globl  resolve_foobar
+resolve_foobar:
+  pushq   %rbp
+  movq    %rsp, %rbp
+  movq    real_foobar@GOTPCREL(%rip), %rax
+  popq    %rbp
+  ret
+
+.globl  foobar
+.type   foobar, @gnu_indirect_function
+.set    foobar, resolve_foobar
+
+.data
+.Lmsg:
+.string "Hello world\n"
+EOF
+
+clang -fuse-ld=`pwd`/../mold -shared -o $t/b.so $t/a.o
+readelf --dyn-syms $t/b.so | grep -Pq '0 FUNC    GLOBAL DEFAULT   \d+ foobar'
+
+echo OK