prefer (X ? 1 : -1) when converting from boolean (1,0) to int (1,-1)

[pspp] / .gitattributes

# See lib/git-merge-changelog.c for making this useful.
ChangeLog       merge=merge-changelog

# Run this to make 'git diff' on texinfo files give nicer hunk context:
#   git config diff.texinfo.funcname '^@node[    ][      ]*\\([^,][^,]*\\)'
*.texi* diff=texinfo