fix issues with calling convention in Kermit SSH DLL

- only layer on Kermit side (ckossh.c) was defined but the same layer must be present on DLL side (ckolssh.c or ckonssh.c) to work properly with different compilers
- 64-bit Windows has defined ABI for DLL that default calling convention is used
- 32-bit systems has not defined ABI for DLL therefore any calling convention can be used, to simplify it cdecl calling convention is used for all 32-bit platforms, it enable to use DLL by any other compiler without dependency on compiler default calling convention
- fix prototypes to use (void) if no parameters are passed, K&R syntax () means any parameters, newer C standards don't permit mixing with K&R syntax and it is reported by some compilers as parameter passing issue
- the DLL export of the ssh_impl_ver function has been removed because no application uses it by exported symbol, it is used by internal access

kermit/k95/ckoker.mak

@@ -1387,7 +1387,7 @@ nullssh.dll: ckonssh.obj ckoker.mak
 !else
 !if "$(CMP)" == "OWWCL"
     $(CC) $(CC2) $(DEBUG) $(DLL) ckonssh.obj $(OUT)$@ \
-	    $(LINKFLAGS_DLL) $(LIBS) -"export ssh_dll_init"
+	    $(LINKFLAGS_DLL) $(LIBS) -"export ssh_dll_init=_ssh_dll_init"
 !endif
 !endif