Since a colleague left I have to proceed with adapting his project. However while running 'make' it seems to fail to compile everything.
The OS is Ubuntu 20.04 (Focal Fossa) running under WSL-2 (this worked for my colleague so that should not be the issue).
depbase=`echo fclose.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
gcc -I. -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -O2 -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -MT fclose.o -MD -MP -MF $depbase.Tpo -c -o fclose.o fclose.c &&\
mv -f $depbase.Tpo $depbase.Po
depbase=`echo fcntl.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
gcc -I. -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -O2 -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -MT fcntl.o -MD -MP -MF $depbase.Tpo -c -o fcntl.o fcntl.c &&\
mv -f $depbase.Tpo $depbase.Po
depbase=`echo fflush.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
gcc -I. -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -O2 -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -MT fflush.o -MD -MP -MF $depbase.Tpo -c -o fflush.o fflush.c &&\
mv -f $depbase.Tpo $depbase.Po
depbase=`echo fpurge.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
gcc -I. -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -O2 -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -MT fpurge.o -MD -MP -MF $depbase.Tpo -c -o fpurge.o fpurge.c &&\
mv -f $depbase.Tpo $depbase.Po
depbase=`echo freadahead.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
gcc -I. -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -O2 -I/home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/host/include -MT freadahead.o -MD -MP -MF $depbase.Tpo -c -o freadahead.o freadahead.c &&\
mv -f $depbase.Tpo $depbase.Po
freadahead.c: In function 'freadahead':
freadahead.c:91:3: error: #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread, ungetc on your system, then report this to bug-gnulib."
91 | #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread, ungetc on your system, then report this to bug-gnulib."
| ^~~~~
make[8]: *** [Makefile:1837: freadahead.o] Error 1
make[8]: Leaving directory '/home/[username]/RUTSDK/RUT9XX_R_GPL/build_dir/host/m4-1.4.17/lib'
make[7]: *** [Makefile:1602: all] Error 2
make[7]: Leaving directory '/home/[username]/RUTSDK/RUT9XX_R_GPL/build_dir/host/m4-1.4.17/lib'
make[6]: *** [Makefile:1506: all-recursive] Error 1
make[6]: Leaving directory '/home/[username]/RUTSDK/RUT9XX_R_GPL/build_dir/host/m4-1.4.17'
make[5]: *** [Makefile:1461: all] Error 2
make[5]: Leaving directory '/home/[username]/RUTSDK/RUT9XX_R_GPL/build_dir/host/m4-1.4.17'
make[4]: *** [Makefile:31: /home/[username]/RUTSDK/RUT9XX_R_GPL/build_dir/host/m4-1.4.17/.built] Error 2
make[4]: Leaving directory '/home/[username]/RUTSDK/RUT9XX_R_GPL/tools/m4'
make[3]: *** [tools/Makefile:160: tools/m4/compile] Error 2
make[3]: Leaving directory '/home/[username]/RUTSDK/RUT9XX_R_GPL'
make[2]: *** [tools/Makefile:158: /home/[username]/RUTSDK/RUT9XX_R_GPL/staging_dir/target-mips_34kc_uClibc-0.9.33.2/stamp/.tools_install_yynyynynynyyyyyyyyyyyyyyyyyyyyynyyyynnyyynyyyynnynyyyy] Error 2
make[2]: Leaving directory '/home/[username]/RUTSDK/RUT9XX_R_GPL'
make[1]: *** [Makefile:95: world] Error 2
make[1]: Leaving directory '/home/[username]/RUTSDK/RUT9XX_R_GPL'
make: *** [/home/[username]/RUTSDK/RUT9XX_R_GPL/include/toplevel.mk:171: world] Error 2