* module/Makefile.am:
* module/system/vm/assembler.scm: New module, implementing an assembler
for RTL.
* test-suite/Makefile.am:
* test-suite/tests/rtl.test: New test suite.
* module/system/vm/elf.scm (make-elf-symbol*): Add constructor; export
as make-elf-symbol.
(elf-symbol-len): New export.
(write-elf32-symbol, write-elf64-symbol): New helpers.
(write-elf-symbol): New export.
