Fixes and cleanup to elf loader code.

Fixes and cleanup to elf loader code.

base/loader/elf_object.cc:
    - Use program header instead of section headers for loading.
    The old code doesn't work for Alpha/Linux user binaries.

    - Deal properly with single-segment ELF executables (e.g. kernels)...
    haven't tested this but it looks like it matches the functionality
    of the patch the L4::Pistachio guys sent.

    - Factor load symbol code into one common function.

    - Some formatting to match style conventions.

    - Only include libelf stuff in .cc file, not .hh.
base/loader/elf_object.hh:
    - Use program header instead of section headers for loading.
    The old code doesn't work for Alpha/Linux user binaries.

    - Factor load symbol code into one common function.

    - Only include libelf stuff in .cc file, not .hh.

--HG--
extra : convert_revision : 782062d09d43083b01e65cd645c941f49c27640a