Unit testing failure with Bison 3.6.1

[Rafael Laboissiere]

Running the unit testing of mwrap fails against Bison 3.6.1, with the following error message:

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(cd testing; make)
make[2]: Entering directory '/var/data/rlaboiss/debian/PKGS/mwrap/mwrap/testing'
make[2]: warning: jobserver unavailable: using -j1.  Add '+' to parent make rule.
../mwrap -mex test_transfersmex \
        -c test_transfersmex.cc \
        -m test_transfers.m test_transfers.mw
mkoctfile --mex test_transfersmex.cc
../mwrap -cppcomplex \
        -mex test_cpp_complexmex \
        -c test_cpp_complexmex.cc \
        -m test_cpp_complex.m test_cpp_complex.mw
mkoctfile --mex test_cpp_complexmex.cc
../mwrap -c99complex \
        -mex test_c99_complexmex \
        -c test_c99_complexmex.c \
        -m test_c99_complex.m test_c99_complex.mw
mkoctfile --mex test_c99_complexmex.c
../mwrap -cppcomplex test_syntax.mw 2> test_syntax.log
make[2]: [Makefile:30: test_syntax] Error 1 (ignored)
diff test_syntax.log test_syntax.ref
2c2
< Parse error (test_syntax.mw:8): syntax error, unexpected end of file, expecting ';'
---
> Parse error (test_syntax.mw:8): syntax error, unexpected $end, expecting ';'

The patch attached to this issue report fixes the problem.

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