New review comment by agausmann on void-packages repository

https://github.com/void-linux/void-packages/pull/38253#discussion_r928321997

Comment:
It is missing some cflags by the look of it:

- with manual `do_build`:
```
cc -fstack-clash-protection -D_FORTIFY_SOURCE=2 -mtune=generic -O2 -pipe    -fdebug-prefix-map=/builddir/libopensmtpd-0.7=. -I/builddir/libopensmtpd-0.7/ -I/builddir/libopensmtpd-0.7//openbsd-compat/ -Wall -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wshadow -Wpointer-arith -Wcast-qual -Wsign-compare -fPIC -DNEED_RECALLOCARRAY=1 -DNEED_STRLCAT=1 -DNEED_STRLCPY=1 -DNEED_STRTONUM=1      -c -o opensmtpd.o opensmtpd.c
```

- with `build_style=gnu-makefile; make_cmd="make -f Makefile.gnu"`:
```
cc -fstack-clash-protection -D_FORTIFY_SOURCE=2 -mtune=generic -O2 -pipe    -fdebug-prefix-map=/builddir/libopensmtpd-0.7=.      -c -o opensmtpd.o opensmtpd.c
```