Our workaround for cross-compilation has been incorporated upstream.

With automake 1.14 there are a lot of new warnings related to the way we deal
with MEX files (they are compiled from source files located in a different
tree). Automake wants us to use the 'subdir-objects' option, but it breaks in
our case.

In automake 2.0, the 'subdir-objects' option will be activated by default, so
we will have to refactor the build system for MEX files. But for now we can
live with the automake warnings.

This reverts commit 7541bb52.

This commit was breaking compilation of MEX files: the subdir-objects option
does not deal well with source files that are under a distinct tree.

Ref 1d14ff80

Build system: remove warning about parentheses (we know the priority rules of C++, no need to be reminded)

Build system: fix minor bug in display of configure script (Dynare++ testsuite had incorrect information due to testing the wrong variable)

Estimation DLL, dynamic DLL loading: minor changes to testModelSolution (now takes the full name of the dynamic DLL in argument)