DOCBOOK_SUPPRESS_SP with docbook-sxl 1.71.0

Hi Junio,

Whenever I install a new git, I always re-build the documentation
(on Linux) rather than use the pre-built html and manpages.
(BTW, I actually don't know why; it's just a habit now:)

From the Documentation/Makefile, it seems there may be some

speculation if DOCBOOK_SUPPRESS_SP should be set when using the
docbook-xsl version 1.71.0.

I am using asciidoc version 7.1.2 along with docbook-xsl version
1.71.0, and I can confirm that setting DOCBOOK_SUPPRESS_SP is
required. (The manpages are *unusable* otherwise)

[I'm sorry, but I don't know the xmlto version number and I can't
get to my linux box ATM]

ATB,
Ramsay Jones