PATCH: Run V3 tests on installed compiler

[Gabriel Dos Reis]

Mark Mitchell <mark@codesourcery.com> writes:

[...]

| Any objections?

Puzzling.

| 
| (Minor note: libstdc++.exp uses "v3-" as a prefix for some functions;
| it should really be using "libstdc++_" as that is the convention for
| tool configuration files.)
| 
| Tested (in the build directory) with and without "--target_board
| 'unix{-32,}'" on x86_64-unknown-linux-gnu, and on an installed
| compiler for both x86_64-unknown-linux-gnu and arm-none-abi.  Applied
| on the mainline; will shortly be applied on the csl-arm-branch as
| well.

-- Gaby