I got past the previous build failure by setting the environment
variable "TAR=noop" (found in the Nix package [0])... who knows what
that means? It only appears in the Nix packaging.

So now, using the attached patch, it fails to build because it can't
find limits.h, as shown below. Any ideas?

------
gcc -o gpsd-3.22/drivers/driver_greis_checksum.os -c -O2 -fPIC -I/gnu/store/00bkkmzybyfmbhhv0nw7r49m72339lyf-dbus-1.12.16/include/dbus-1.0 -I/gnu/store/00bkkmzybyfmbhhv0nw7r49m72339lyf-dbus-1.12.16/lib/dbus-1.0/include gpsd-3.22/drivers/driver_greis_checksum.c
In file included from /gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/include/bits/posix1_lim.h:161:0,
                 from /gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/include/limits.h:183,
                 from /gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib/lib/gcc/x86_64-unknown-linux-gnu/7.5.0/include-fixed/limits.h:194,
                 from /gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib/lib/gcc/x86_64-unknown-linux-gnu/7.5.0/include-fixed/syslimits.h:7,
                 from /gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib/lib/gcc/x86_64-unknown-linux-gnu/7.5.0/include-fixed/limits.h:34,
                 from gpsd-3.22/drivers/driver_greis_checksum.c:11:
/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/include/bits/local_lim.h:38:10: fatal error: linux/limits.h: No such file or directory
 #include <linux/limits.h>
          ^~~~~~~~~~~~~~~~
compilation terminated.
gcc -o gpsd-3.22/drivers/driver_rtcm2.os -c -O2 -fPIC -I/gnu/store/00bkkmzybyfmbhhv0nw7r49m72339lyf-dbus-1.12.16/include/dbus-1.0 -I/gnu/store/00bkkmzybyfmbhhv0nw7r49m72339lyf-dbus-1.12.16/lib/dbus-1.0/include gpsd-3.22/drivers/driver_rtcm2.c
scons: *** [gpsd-3.22/drivers/driver_greis_checksum.os] Error 1
In file included from /gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/include/bits/posix1_lim.h:161:0,
                 from /gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/include/limits.h:183,
                 from /gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib/lib/gcc/x86_64-unknown-linux-gnu/7.5.0/include-fixed/limits.h:194,
                 from /gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib/lib/gcc/x86_64-unknown-linux-gnu/7.5.0/include-fixed/syslimits.h:7,
                 from /gnu/store/01b4w3m6mp55y531kyi1g8shh722kwqm-gcc-7.5.0-lib/lib/gcc/x86_64-unknown-linux-gnu/7.5.0/include-fixed/limits.h:34,
                 from gpsd-3.22/drivers/../include/gps.h:14,
                 from gpsd-3.22/drivers/../include/gpsd.h:29,
                 from gpsd-3.22/drivers/driver_rtcm2.c:65:
/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/include/bits/local_lim.h:38:10: fatal error: linux/limits.h: No such file or directory
 #include <linux/limits.h>
          ^~~~~~~~~~~~~~~~
compilation terminated.
scons: *** [gpsd-3.22/drivers/driver_rtcm2.os] Error 1
scons: building terminated because of errors.
------

[0]
https://github.com/NixOS/nixpkgs/blob/b166cc7fddc7c9b3fdd27dd74f177116ee5e2a7b/pkgs/servers/gpsd/default.nix#L54