ash: add LINENO support

This patch is a backport from dash of the combination of:
    [SHELL] Add preliminary LINENO support
    [VAR] Fix varinit ordering that broke fc
    [SHELL] Improve LINENO support

function                                             old     new   delta
parse_command                                       1604    1677     +73
calcsize                                             156     223     +67
copynode                                             196     258     +62
evalcommand                                         1546    1606     +60
ash_main                                            1046    1103     +57
lookupvar                                             51     106     +55
evalcase                                             269     317     +48
evaltree                                             501     547     +46
evalfor                                              156     200     +44
evalsubshell                                         156     195     +39
raise_error_syntax                                    11      29     +18
varinit_data                                         120     132     +12
evalfun                                              270     280     +10
funcline                                               -       4      +4
cmdtxt                                               569     572      +3
trapcmd                                              306     304      -2
ash_vmsg                                             153     150      -3
startlinno                                             4       -      -4
funcnest                                               4       -      -4
xxreadtoken                                          263     250     -13
readtoken1                                          2645    2602     -43
------------------------------------------------------------------------------
(add/remove: 1/2 grow/shrink: 14/4 up/down: 598/-69)          Total: 529 bytes
   text	   data	    bss	    dec	    hex	filename
 932834	    481	   6864	 940179	  e5893	busybox_old
 933375	    481	   6856	 940712	  e5aa8	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash_test/ash-psubst/emptytick.right b/shell/ash_test/ash-psubst/emptytick.right
index 7629deb..459c4f7 100644
--- a/shell/ash_test/ash-psubst/emptytick.right
+++ b/shell/ash_test/ash-psubst/emptytick.right
@@ -1,8 +1,8 @@
 0
 0
-./emptytick.tests: line 3: : Permission denied
+./emptytick.tests: line 1: : Permission denied
 127
-./emptytick.tests: line 4: : Permission denied
+./emptytick.tests: line 1: : Permission denied
 127
 0
 0