Fix prints in tests for Python 3

Fix prints in tests for Python 3

Python 3's print requires to use parentheses, so this patch adds them
where they were missing.

gdb/testsuite/ChangeLog:

	* gdb.ada/py_range.exp: Add parentheses to calls to print.
	* gdb.dwarf2/symtab-producer.exp: Same.
	* gdb.gdb/python-interrupts.exp: Same.
	* gdb.gdb/python-selftest.exp: Same.
	* gdb.python/py-linetable.exp: Same.
	* gdb.python/py-type.exp: Same.
	* gdb.python/py-value-cc.exp: Same.
	* gdb.python/py-value.exp: Same.