There is no need to compile our DLLs as shared libraries since we are
managing symbols exports and imports through spec files.
On my system, this reduces the configure-time by a factor of two.
Indeed, rosautotest has an annoying tendency to fail with:
Invalid test file name: <testname>.exe
SYSREG_ROSAUTOTEST_FAILURE
when <testname>.exe is a test that do not comply with the rosautotest
interface.
This is indeed the case for all the tests under /rostests/win32/, with the
exception of cmd_rostest.
Addendum to 8dd89c7.
