RosBE for UNIX does not include m4

On a fresh installation of Ubuntu 20.04.02 LTS (via the multipass downloader), I updated the OS (`sudo apt update; sudo apt upgrade`).  I then followed the instructions on the "Building ReactOS" wiki page to install the rosbe-unix package.

I then cloned the github repository for reactos/reactos, entered that directory, followed the instructions to start RosBE, ran ./configure.sh, entered the output-MinGW-i386 directory, and ran ninja.

The following is abridged from the output that ninja returned of the failure.  (After this, I did `sudo apt install m4`, then restarted ninja, and it continued properly.)  Since m4 is a dependency, I believe m4 should be added to RosBE curation.

[62/10744] Performing build step for 'host-tools'
FAILED: host-tools/src/host-tools-stamp/host-tools-build host-tools/bin/bin2c host-tools/bin/widl host-tools/bin/gendib host-tools/bin/cabman host-tools/bin/fatten host-tools/bin/hpp host-tools/bin/isohybrid host-tools/bin/mkhive host-tools/bin/mkisofs host-tools/bin/obj2bin host-tools/bin/spec2def host-tools/bin/geninc host-tools/bin/mkshelllink host-tools/bin/txt2nls host-tools/bin/utf16le host-tools/bin/xml2sdb host-tools/bin/rsym host-tools/bin/pefixup

[...]

[208/292] [BISON][pp_parser] Building parser with bison 3.5.4
FAILED: sdk/tools/wpp/ppy.tab.c sdk/tools/wpp/ppy.tab.h
cd /home/ubuntu/work/reactos/output-MinGW-i386/host-tools/bin/sdk/tools/wpp && /usr/RosBE/bin/bison -p ppy_ -d -o /home/ubuntu/work/reactos/output-MinGW-i386/host-tools/bin/sdk/tools/wpp/ppy.tab.c /home/ubuntu/work/reactos/sdk/tools/wpp/ppy.y
/usr/RosBE/bin/bison: m4 subprocess failed: No such file or directory
[209/292] Building C object sdk/tools/unicode/CMakeFiles/unicode.dir/wctype.c.o
ninja: build stopped: subcommand failed.
[63/10744] Building C object sdk/lib/3rdparty/freetype/CMakeFiles/freetype.dir/src/cid/type1cid.c.obj
ninja: build stopped: subcommand failed.