Fix archive writer

1. align to even address
2. Fix the use of GElf_Ehdr and Elf32_Ehdr
RA format support for rtems-ld

1. Automatically place object files in archive files into a ra file,
   using new option --runtime-lib
2. Add a new option --one-file to decide whether the collected
   object files should be merged into the rap file or not.
Added a new tool

The new tool is for converting elf archive file into rap archive file.
Ignore common section and null(index 0) section