[ELF] Do not error for missing version when symbol has local version.

If a symbol with an undefined version in a DSO is not going to be
exported into the dynamic symbol table then do not give an error message
for the missing version. This can happen with the --exclude-libs option
which implicitly gives all symbols in a static library the local version.
This matches the behavior of ld.gold and is exploited by the Bionic
dynamic linker on Arm.

Differential Revision: https://reviews.llvm.org/D43126

llvm-svn: 332224