Limit the maximum alignment of copyrel'ed shared symbols to 32.

[ruiu]

Summary

When we create a copy relocation, we need to compute its alignment.
Since the information is lost already, we need to infer it from a
symbol address.

If a symbol seems to be aligned to a very large address, it is likely
that it doesn't really need that alignment but it happens to get that
address. So, for example, if a symbol's address is 6 GiB, it usually
doesn't mean that it must be aligned to 2 GiB.

This patch limits the maximum alignment to 32. 32 is chosen as a
"reasonable" maximum alignment.

[ruiu]

• Address review comments.

[ruiu]

• Fix build error.

lld/trunk/ELF/InputFiles.cpp

if (VersymIndex != VER_NDX_GLOBAL) {
       }
       Ver = Verdefs[VersymIndex];
     }
 
     // We do not usually care about alignments of data in shared object
     // files because the loader takes care of it. However, if we promote a
     // DSO symbol to point to .bss due to copy relocation, we need to keep
     // the original alignment requirements. We infer it here.
-    uint32_t Alignment = 1;
+    uint64_t Alignment = 1;
     if (Sym.st_value)
       Alignment = 1ULL << countTrailingZeros((uint64_t)Sym.st_value);
     if (0 < Sym.st_shndx && Sym.st_shndx < Sections.size()) {
-      uint32_t SecAlign = Sections[Sym.st_shndx].sh_addralign;
+      uint64_t SecAlign = Sections[Sym.st_shndx].sh_addralign;
       Alignment = std::min(Alignment, SecAlign);
     }
+    if (Alignment > UINT32_MAX)
+      error(toString(this) + ": alignment too large: " + Name);
 
     if (!Hidden)
       Symtab->addShared(Name, this, Sym, Alignment, Ver);
 
     // Also add the symbol with the versioned name to handle undefined symbols
     // with explicit versions.
     if (Ver) {
       StringRef VerName = this->StringTable.data() + Ver->getAux()->vda_name;