ash: get rid of two global data variables

ash: get rid of two global data variables

function                                             old     new   delta
calcsize                                             126     147     +21
funcstring_end                                         -       4      +4
sizenodelist                                          28      24      -4
funcstringsize                                         4       -      -4
funcstring                                             4       -      -4
funcblocksize                                          4       -      -4
nodeckstrdup                                          48      39      -9
evaltree                                             828     788     -40
------------------------------------------------------------------------------
(add/remove: 1/3 grow/shrink: 1/4 up/down: 25/-105)           Total: -40 bytes
   text	   data	    bss	    dec	    hex	filename
 943376	    916	  14292	 958584	  ea078	busybox_old
 943344	    916	  14284	 958544	  ea050	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>