[v3] unify 3_4 and 3_5 libstdc++, try two

[Paolo Carlini]

Benjamin Kosnik wrote:

>Can you try this patch? It has the two bits you noticed yesterday. 
>
Great, now everything is fine here:

x86-64
------
XPASS: 26_numerics/c99_classification_macros_c.cc (test for excess errors)
XPASS: 27_io/fpos/14320-1.cc execution test

                === libstdc++ Summary ===

# of expected passes            2629
# of unexpected successes       2
# of expected failures          4

ia64
----
XPASS: 26_numerics/c99_classification_macros_c.cc (test for excess errors)
XPASS: 27_io/fpos/14320-1.cc execution test

                === libstdc++ Summary ===

# of expected passes            2629
# of unexpected successes       2
# of expected failures          4

Paolo.

PS. For ia64 testing I have locally an additional patch to prune.exp
suppressing spurious warnings at build time from the assembler.