demangle.cc: Fix clang compilation issue

This fixes issue #319
6 jobs for master in 3888 minutes and 56 seconds (queued for 2 seconds)
Name Stage Failure
failed
job_gcc_amd64 Test There is an unknown failure, please try again
  warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.5/site-packages/matplotlib/pyplot.py:516: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)
/usr/lib/python3.5/site-packages/matplotlib/tight_layout.py:222: UserWarning: tight_layout : falling back to Agg renderer
warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.5/site-packages/matplotlib/pyplot.py:516: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)

ERROR: Build failed: exit status 1
failed
job_clang_amd64 Test There is an unknown failure, please try again
  max_open_warning, RuntimeWarning)
/usr/lib/python3.5/site-packages/matplotlib/pyplot.py:516: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)
/usr/lib/python3.5/site-packages/matplotlib/pyplot.py:516: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)
/usr/lib/python3.5/site-packages/matplotlib/pyplot.py:516: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)

ERROR: Build failed: exit status 1
failed
job_gcc_py2_amd64 Test There is an unknown failure, please try again

Document: centrality
--------------------

Encoding error:
'ascii' codec can't decode byte 0x83 in position 403: ordinal not in range(128)
The full traceback has been saved in /tmp/sphinx-err-7u5B04.log, if you want to report the issue to the developers.

ERROR: Build failed: exit status 1
failed
job_clang_py2_amd64 Test There is an unknown failure, please try again

Document: centrality
--------------------

Encoding error:
'ascii' codec can't decode byte 0xd1 in position 401: ordinal not in range(128)
The full traceback has been saved in /tmp/sphinx-err-62SKzh.log, if you want to report the issue to the developers.

ERROR: Build failed: exit status 1
failed
job_gcc_amd64_nosh Test There is an unknown failure, please try again
  warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.5/site-packages/matplotlib/pyplot.py:516: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)
/usr/lib/python3.5/site-packages/matplotlib/tight_layout.py:222: UserWarning: tight_layout : falling back to Agg renderer
warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.5/site-packages/matplotlib/pyplot.py:516: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)

ERROR: Build failed: exit status 1
failed
job_clang_amd64_nosh Test There is an unknown failure, please try again
Doctest summary
===============
966 tests
6 failures in tests
0 failures in setup code
0 failures in cleanup code
build finished with problems, 155 warnings.

ERROR: Build failed: exit status 1