Imports of asm command

PathSynopsis
cmd/asm/internal/archPackage arch defines architecture-specific information and support functions.
cmd/asm/internal/asmPackage asm implements the parser and instruction generator for the assembler.
cmd/asm/internal/flagsPackage flags implements top-level flags and the usage message for the assembler.
cmd/asm/internal/lexPackage lex implements lexical analysis for the assembler.
cmd/internal/obj
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
logPackage log implements a simple logging package.
osPackage os provides a platform-independent interface to operating system functionality.