[ELF] Support --no-align-segments.

lld generates an ELF by adhering to the ELF spec by aligning vma/fileoffset to a
page boundary, but this becomes an issue when dealing with large pages. This
adds support so that lld generated executables adheres to the ELF spec with the
rule vma % p_align = offset % p_align.

This is supported by the flag --no-align-segments.

This could be the default in few targets like X86_64 to save space on disk.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@221571 91177308-0d34-0410-b5e6-96231b3b80d8