DKMS build problem on Pinephone with UBports (xenial)

[Jaron Kent-Dobias]

Hello,

Installing the wireguard-dkms package (0.0.20200215-0ppa1~16.04) on a
Pinephone running UBports (xenial with custom repositories) results in a
DKMS build error. The shell output and make.log are below. Seems like a
syntax error in a build script, not sure if this belongs here or downstream.

Jaron

> phablet at ubuntu-phablet ~ % sudo apt install wireguard-dkms
> Reading package lists... Done
> Building dependency tree       
> Reading state information... Done
> Recommended packages:
>   wireguard
> The following NEW packages will be installed:
>   wireguard-dkms
> 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
> Need to get 259 kB of archives.
> After this operation, 1,765 kB of additional disk space will be used.
> Get:1 http://ppa.launchpad.net/wireguard/wireguard/ubuntu xenial/main arm64 wireguard-dkms all 0.0.20200215-0ppa1~16.04 [259 kB] 
> Fetched 259 kB in 0s (279 kB/s)         
> Selecting previously unselected package wireguard-dkms.
> (Reading database ... 83056 files and directories currently installed.)
> Preparing to unpack .../wireguard-dkms_0.0.20200215-0ppa1~16.04_all.deb ...
> Unpacking wireguard-dkms (0.0.20200215-0ppa1~16.04) ...
> Setting up wireguard-dkms (0.0.20200215-0ppa1~16.04) ...
> Loading new wireguard-0.0.20200215 DKMS files...
> First Installation: checking all kernels...
> Building only for 5.4.0-pine64
> Building initial module for 5.4.0-pine64
> Error! Bad return status for module build on kernel: 5.4.0-pine64 (aarch64)
> Consult /var/lib/dkms/wireguard/0.0.20200215/build/make.log for more information.
> W: No sandbox user '_apt' on the system, can not drop privileges
>   11.03s user 4.14s system 83% cpu 18.115 total

> DKMS make.log for wireguard-0.0.20200215 for kernel 5.4.0-pine64 (aarch64)
> Sat Feb 22 19:47:26 UTC 2020
> make: Entering directory '/usr/src/linux-headers-5.4.0-pine64'
>   AR      /var/lib/dkms/wireguard/0.0.20200215/build/built-in.a
>   CC [M]  /var/lib/dkms/wireguard/0.0.20200215/build/main.o
> scripts/basic/fixdep: 1: scripts/basic/fixdep: Syntax error: ")" unexpected
> scripts/Makefile.build:265: recipe for target '/var/lib/dkms/wireguard/0.0.20200215/build/main.o' failed
> make[1]: *** [/var/lib/dkms/wireguard/0.0.20200215/build/main.o] Error 2
> make[1]: *** Deleting file '/var/lib/dkms/wireguard/0.0.20200215/build/main.o'
> Makefile:1652: recipe for target '/var/lib/dkms/wireguard/0.0.20200215/build' failed
> make: *** [/var/lib/dkms/wireguard/0.0.20200215/build] Error 2
> make: Leaving directory '/usr/src/linux-headers-5.4.0-pine64'