add alignment to .got/.got.plt/.plt sections & fix tests

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@174199 91177308-0d34-0410-b5e6-96231b3b80d8
remove duplicate strings from the string table

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@174200 91177308-0d34-0410-b5e6-96231b3b80d8