Ensured that all assembly files have consistent indentation.
Implemented platform support for Linux (x86).
Ensured that HOST_TYPE is set to 'posix' on POSIX platforms.
Defined the <stdio.h> stdin, stdout, and stderr streams.
Reorganized the platform support code on DRY principles.
Implemented the <stdio.h> stream objects for POSIX platforms.
Implemented the <stdio.h> fputs() function.
Implemented the <stdio.h> fputc() and putc() functions.
Implemented the <stdio.h> putchar() function.
Implemented the <stdio.h> ferror() function.
Implemented the <stdio.h> clearerr() function.
Implemented the <stdio.h> fflush() and fclose() functions.
Implemented the __sys_close() operation for all platforms.