[Groff] pic breaks with bison

[Alejandro Lopez-Valencia]

but not with byacc?

hmmm... I did a serious hard-drive cleaning and among the things I thought 
I would not need was byacc. But the version of bison I have (version 
1.875b) either is broken, or pic.y has bugs. With byacc I get no conflicts, 
with bison I get 8 shift/reduce conflicts and the resulting binary is 
useless; while processing the pic manual during an otherwise normal build, 
I get:

"""
pic:<standard input>:113: syntax error before `width'
pic:<standard input>:113: giving up on this picture
        .
        .
        .
pic:<standard input>:351: giving up on this picture
/tmp/groff_build/src/roff/groff/groff: pic: Signal 11 (core dumped)
make[2]: *** [pic.ps] Error 2
        .
        .
        .
"""