[ELF] Fix functionality treating IFunc definitions in DSOs as functions.

[grimar]

Summary

It was intially implemented in D19517 but then broken.
Patch fixes PR33707, testcase is based on PR's case.

[ruiu]

LGTM. This is a nasty bug, thank you for finding one.

lld/trunk/ELF/Symbols.h

public:
   }
 
   SharedSymbol(InputFile *File, StringRef Name, uint8_t StOther, uint8_t Type,
                const void *ElfSym, const void *Verdef)
       : Defined(SymbolBody::SharedKind, Name, /*IsLocal=*/false, StOther, Type),
         Verdef(Verdef), ElfSym(ElfSym) {
     // IFuncs defined in DSOs are treated as functions by the static linker.
     if (isGnuIFunc())
-      Type = llvm::ELF::STT_FUNC;
+      this->Type = llvm::ELF::STT_FUNC;
     this->File = File;
   }
 
   template <class ELFT> uint64_t getShndx() const {
     return getSym<ELFT>().st_shndx;
   }
 
   template <class ELFT> uint64_t getValue() const {

lld/trunk/test/ELF/Inputs/gnu-ifunc-dso.s

+.type foo STT_GNU_IFUNC
+.globl foo
+foo:

lld/trunk/test/ELF/gnu-ifunc-dso.s

+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/gnu-ifunc-dso.s -o %t1.o
+# RUN: ld.lld -shared %t1.o -o %t.so
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t2.o
+# RUN: ld.lld -shared %t2.o %t.so -o %t
+# RUN: llvm-readobj -dyn-relocations %t | FileCheck %s
+
+# CHECK:      Dynamic Relocations {
+# CHECK-NEXT:   0x1000 R_X86_64_64 foo 0x0
+# CHECK-NEXT: }
+
+.data
+ .quad foo