support debhelper 10

[bkw777]

support debhelper 10

[Uldiniad]

I'm having the same issue on Ubuntu 20.04

[bkw777]

I just discovered that I get the same failure if I use make -j 8 (or any number) even with compat still set to 9.

[bkw777]

... and the manual for debhelper does say that it does do parallel builds by default starting with version 10
https://www.man7.org/linux/man-pages/man7/debhelper.7.html

       --parallel, --no-parallel
           Control whether parallel builds should be used if underlying
           build system supports them.  The number of parallel jobs is
           controlled by the DEB_BUILD_OPTIONS environment variable
           ("Debian Policy, section 4.9.1") at build time. It might also
           be subject to a build system specific limit.

           If neither option is specified, debhelper currently defaults
           to --parallel in compat 10 (or later) and --no-parallel
           otherwise.

           As an optimization, dh will try to avoid passing these
           options to subprocesses, if they are unnecessary and the only
           options passed.  Notably this happens when DEB_BUILD_OPTIONS
           does not have a parallel parameter (or its value is 1).

[bkw777]

should be fixed by 980ab38
I put debian/compat = 13 rather than 10, so I don't know if that will cause a problem building on older targets, but I guess we'll see.