configure: set -Wno-error-overloaded-virtual for clang builds

When compiling with clang, several locations in the code emit the
warning -Woverloaded-virtual. That warning is not trivial to fix. In order
to allow CXX=clang++ ABIGAIL_DEVEL=1 development, demote the warning to
not be an error when compiling with clang.

	* configure.ac: set -Wno-error-overloaded-virtual for clang++

Signed-off-by: Matthias Maennich <maennich@google.com>
1 file changed