Fix the return type of GIN triConsistent support functions to "char".

They were marked to return a boolean, but they actually return a
GinTernaryValue, which is more like a "char". It makes no practical
difference, as the triConsistent functions cannot be called directly from
SQL because they have "internal" arguments, but this nevertheless seems
more correct.

Also fix the GinTernaryValue name in the documentation. I renamed the enum
earlier, but neglected the docs.

Alexander Korotkov. This is new in 9.4, so backpatch there.
Fix TAP checks when current directory name contains spaces

Add some quotes in the makefile snippet that creates the temporary
installation, so that it can handle spaces in the directory name and
possibly some other oddities.