[dwarfdump] Dump DW_AT_ranges values inline in the debug_info dump.

The output looks like that:
                      DW_AT_ranges [FORM_data4]    (0x00000000
                         [0x00000001000024a0 - 0x00000001000024c2)
                         [0x0000000100002505 - 0x000000010000268b))

Differential Revision: http://reviews.llvm.org/D5712
Modernize doxygen comments in Support/Dwarf.h

In post-commit review of r219442, Rafael pointed out that the comment style
of the newly introduced helper didn't follow LLVM's coding standard.
Modernize the whole file to the new standards.

Differential Revision: http://reviews.llvm.org/D5918