* tests/cxxsupp.cxx: Added this test program to check that basic C++ support is present. It checks that pure virtual functions can be defined, that new and delete are present and functional, and that calls to as-yet undefined inline functions work. Most of these are linker and runtime system issues, so the actual run of the program is almost a non-event. * cdl/infra.cdl: Added CYGFUN_INFRA_DUMMY_ABORT and CYGFUN_INFRA_DUMMY_STRLEN options to conrol inclusion of dummy abort() and strlen() functions. These are needed to be present by the compiler's C++ runtime system, although they should never be called. Added CYGPKG_INFRA_TESTS to define test programs. Added CYGPKG_INFRA_LDFLAGS_REMOVE and CYGPKG_INFRA_LDFLAGS_ADD to modify the linkage options for the infra package tests. Specifically they remove the --gc-sections option and make all linker warning fatal. This is necessary if cxxsupp.cxx is to test what it needs correctly. * src/abort.cxx: Added this dummy implementation of abort() to satisfy references in the C++ runtime system. * src/strlen.cxx: Added this dummy implementation of strlen() to satisfy references in the C++ runtime system.