* configure,configure.in: Add target sparclet.

* configure,configure.in: Add target sparclet.
    * monitor.h,monitor.c:
    Added monitor flags MO_NO_ECHO_ON_SETMEM (don't expect echo on
    setmem command), MO_RUN_FIRST_TIME (if command to start process
    running on target is different from one to continue execution),
    MO_HEX_PREFIX (if addresses from monitor have a "0x" prefix).
    * monitor.c,parse.c,sparc-tdep.c:
    Don't require strings in the registers array.  This is to allow
    NULLs to be place holders in the tm-*.h file so that only minor
    changes are needed when a new processor is introduced (eg, one
    without floating point).
    * sparc-tdep.c: Conditionally remove dependancies on floating point.
    * sparclet-rom.c,config/sparc/sparclet.mt,config/sparc/tm-sparclet.h:
    New files for target sparclet.
    * symfile.c: Add option for 2nd parameter on load command : a load
    offset added to the vma of each section.