[patch, 3.4] Fix PR c++/24103

[Gabriel Dos Reis]

Volker Reichelt <reichelt@igpm.rwth-aachen.de> writes:

| The following patch fixes an ice-on-valid-code with compound literals
| as default arguments.
| The reason for the ICE is that simple_cst_equal's support for
| constructors is incomplete, it simply calls abort in cases it
| cannot handle.
| 
| This was fixed on the tree-ssa branch by Diego's patch below. The fix
| was then merged into mainline. The code in question still looks like
| this on the 4.0 branch, i.e. it received a lot of testing.
| (It changed slightly on mainline and the 4.1 branch because the tree
| lists were replaced by VECs.)
| 
| Bootstrapped and regtested on i686-pc-linux-gnu.
| Ok for the 3.4 branch?

Yes, thanks.

| 
| What about the testcase?
| Ok for mainline, 4.0 branch, and 4.1 branch, too?

I think the testcase shoulkd go there too, to make sure we don't
regress in that department.

-- Gaby