executable file "${binfile}", C++ version "${binfile}-cxx".
* gdb.python/py-prettyprint.exp: Likewise.
* gdb.python/py-symbol.exp: Likewise.
* gdb.python/py-type.exp: Likewise.
* gdb.python/py-value.exp: Likewise.
* gdb.python/py-template.exp (test_template_arg): Pass full executable
file name instead of just suffix.