Bug#710336: some observations

[Michael Cree <mcree@orcon.net.nz>]

Control: tags 710336 + patch

Actually the fix is obvious.  Patch attached.  Passes test suite and builds
to completion on armel and alpha.

Cheers
Michael

--- graphite2-1.2.1-orig/src/Pass.cpp	2013-02-28 08:32:04.000000000 +1300
+++ graphite2-1.2.1/src/Pass.cpp	2013-06-02 11:26:52.004522217 +1200
@@ -195,7 +195,8 @@ bool Pass::readRules(const byte * rule_m
         if (r->sort > 63 || r->preContext >= r->sort || r->preContext > m_maxPreCtxt || r->preContext < m_minPreCtxt)
             return false;
         ac_begin      = ac_data + be::peek<uint16>(--o_action);
-        rc_begin      = *--o_constraint ? rc_data + be::peek<uint16>(o_constraint) : rc_end;
+	--o_constraint;
+        rc_begin      = be::peek<uint16>(o_constraint) ? rc_data + be::peek<uint16>(o_constraint) : rc_end;
 
         if (ac_begin > ac_end || ac_begin > ac_data_end || ac_end > ac_data_end
                 || rc_begin > rc_end || rc_begin > rc_data_end || rc_end > rc_data_end)