Verify that archive extraction flags really are supported on Solaris before overriding MKSHLIB_FORCE_ALL.

configure.in

@@ -499,8 +499,10 @@ dnl the qsort routine under solaris is faulty
     else
        MKSHLIB='$(CXX) $(DSO_LDOPTS)'
        MKCSHLIB='$(CC) $(DSO_LDOPTS)'
+       if test "$ac_cv_mkshlib_force_and_unforce" != "no"; then
        MKSHLIB_FORCE_ALL='-z allextract'
        MKSHLIB_UNFORCE_ALL=''
+       fi
        DSO_LDOPTS='-G -h $(@:$(OBJDIR)/%.$(DLL_SUFFIX)=%.$(DLL_SUFFIX))'
        _WARNINGS_CFLAGS=''
        _WARNINGS_CXXFLAGS=''