Fixing tiny syntax errors occurring during compilation.

There are three tiny syntax errors in total. I am not sure what to do for the third one.

byte-compiling /usr/local/lib/python2.7/dist-packages/sympy/mpmath/tests/extratest_gamma.py to extratest_gamma.pyc
SyntaxError: ('invalid syntax', ('/usr/local/lib/python2.7/dist-packages/sympy/mpmath/tests/extratest_gamma.py', 50, 35, '        print("%s ok;" % name, end=\' \')\n'))

byte-compiling /usr/local/lib/python2.7/dist-packages/sympy/mpmath/tests/torture.py to torture.pyc
SyntaxError: ('invalid syntax', ('/usr/local/lib/python2.7/dist-packages/sympy/mpmath/tests/torture.py', 80, 27, '            print(".", end=\' \')\n'))

byte-compiling /usr/local/lib/python2.7/dist-packages/sympy/mpmath/libmp/exec_py3.py to exec_py3.pyc
SyntaxError: ('invalid syntax', ('/usr/local/lib/python2.7/dist-packages/sympy/mpmath/libmp/exec_py3.py', 1, 12, 'exec_ = exec\n'))