[Ada] fix spitbol bug

[Arnaud Charlet]

Tested on i686-linux, committed on trunk.

If a one character string is used as a parameter to one of the spitbol
pattern matching routines, and the lower bound is other than one (this
most typically happens from the use of a slice), then the routine may
malfunction. This is because there was an explicit use of Str (0) which
should have been Str (Str'First) in S_To_PE.

See gnat.dg/spipaterr.adb

2006-10-31  Robert Dewar  <dewar@adacore.com>

	* g-spipat.adb (S_To_PE): Remove incorrect use of 0 instead of Str'First

-------------- next part --------------
Index: g-spipat.adb
===================================================================
--- g-spipat.adb	(revision 118179)
+++ g-spipat.adb	(working copy)
@@ -3431,7 +3431,7 @@ package body GNAT.Spitbol.Patterns is
             return new PE'(PC_Null,     1, EOP);
 
          when 1 =>
-            return new PE'(PC_Char,     1, EOP, Str (1));
+            return new PE'(PC_Char,     1, EOP, Str (Str'First));
 
          when 2 =>
             return new PE'(PC_String_2, 1, EOP, Str);