compiler/arm/call: added COMPUTE-OLD-NPF VOP

  * taken from the MIPS
code/late-type: commented out float related stuff

  * I used #+sb-xc-host and #sb-xc-host this time, because
    I could not get it to work with #!-arm.
code/defsetfs: commented out float related stuff
code/defstruct: commented out float related stuff
code/target-defstruct: commented out float related stuff
compiler/arm/cell: added defstruct related VOPs

  * RAW-INSTANCE-REF/WORD and RAW-INSTANCE-SET-WORD taken from
    MIPS
compiler/arm/system: fixed usage of negative immediate
compiler/srctran: commented out float related stuff

  * used #+sb-xc-host and #-sb-xc-host again instead of #!-arm
compiler/arm/macros: removed unused let bound SCALE
compiler/arm/macros: fixed LOAD-SYMBOL

  * the return value of STATIC-SYMBOL-OFFSET seems to not always fit
    into an ARM immediate, so I use the composite instruction macro
compiler/arm/move: removed unused label and temporary
compiler/arm/arith: removed unused temporary
compiler/arm/call: various adjustments to appease compiler

  * removed unused temporaries and labels
  * removed a false declaration
  * added an ignore declaration
compiler/arm/type-vops: declared unused keyword ignored
compiler/arm/system: added dummy for SPIN-LOOP-HINT VOP from ALPHA
compiler/arm/alloc: added VOP ALLOCATE-CODE-OBJECT

  * adjusted from MIPS and PPC versions
code/target-sap: replaced float releated code with error signaling code for ARM
code/target-random: replaced float related code with error signaling code for ARM