_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE, RPI4b

[Danrancan]

After building with the make command on a raspberrry pi 4b, I get the following warning:

[fauxcon] gcc -std=gnu99 -ggdb3 -O0 -Wall -Wextra -Wunused '-DVERSION="0.1.0-6-g5585812"' -c fauxcon.c -o fauxcon.o
In file included from /usr/include/aarch64-linux-gnu/bits/libc-header-start.h:33,
                 from /usr/include/stdio.h:27,
                 from fauxcon.c:35:
/usr/include/features.h:187:3: warning: #warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE" [-Wcpp]
  187 | # warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"

Not sure what this warning means, as there are no build instructions for this application.