NetBSD-10 openssl/types.h:96:1: error: data definition has no type or storage class

[Sad Clouds <cryintothebluesky%gmail.com@localhost>]

I'm trying to build NetBSD-10 on Solaris-11.4 and noticing various
portability issues that result in build failures.

The last one is related to missing OpenSSL types:

#   compile  libtelnet/pk.o
/opt/netbsd/tools.sparc64/bin/sparc64--netbsd-gcc -O2 -fdebug-prefix-map=\$DESTDIR= -fdebug-prefix-map=\$NETBSDSRCDIR=/u
sr/src -fdebug-prefix-map=\$X11SRCDIR=/usr/xsrc -fdebug-regex-map='/usr/src/(.*)/obj$=/usr/obj/\1' -fdebug-regex-map='/u
sr/src/(.*)/obj/(.*)=/usr/obj/\1/\2' -fdebug-regex-map='/usr/src/(.*)/obj\..*=/usr/obj/\1' -fdebug-regex-map='/usr/src/(
.*)/obj\..*/(.*)=/usr/obj/\1/\2'   -std=gnu99    -Wall -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wno-sig
n-compare  -Wsystem-headers   -Wno-traditional   -Wa,--fatal-warnings  -Wreturn-type -Wswitch -Wshadow -Wcast-qual -Wwri
te-strings -Wextra -Wno-unused-parameter -Wno-sign-compare -Wold-style-definition -Wsign-compare -Wformat=2  -Wno-format
-zero-length  -Werror  -mcpu=ultrasparc -fPIE -fstack-protector -Wstack-protector   --param ssp-buffer-size=1    --sysro
ot=/opt/netbsd/obj.sparc64/destdir.sparc64 -DHAS_CGETENT -I/opt/netbsd/netbsd-10-src/lib/libtelnet -DENCRYPTION -DAUTHEN
TICATION -DDES_ENCRYPTION -DKRB5 -DSRA -Wp,-iremap,/opt/netbsd/obj.sparc64/destdir.sparc64: -Wp,-fno-canonical-system-he
aders -Wp,-iremap,/opt/netbsd/netbsd-10-src:/usr/src -Wp,-iremap,/opt/netbsd/xsrc:/usr/xsrc  -D_FORTIFY_SOURCE=2 -c -Wno
-pointer-sign   /opt/netbsd/netbsd-10-src/lib/libtelnet/pk.c -o pk.o
In file included from /opt/netbsd/obj.sparc64/destdir.sparc64/usr/include/openssl/bn.h:25,
                 from /opt/netbsd/netbsd-10-src/lib/libtelnet/pk.c:52:
/opt/netbsd/obj.sparc64/destdir.sparc64/usr/include/openssl/types.h:96:1: error: data definition has no type or storage 
class [-Werror]
   96 | STACK_OF(BIGNUM);
      | ^~~~~~~~

As far as I can tell, these macros should be in <openssl/safestack.h>
header but this file is empty in destdir:

ls -l /opt/netbsd/obj.sparc64/destdir.sparc64/usr/include/openssl/safestack.h 
-r--r--r--   1 root    root          0 Mar 26 09:17 /opt/netbsd/obj.sparc64/destdir.sparc64/usr/include/openssl/safestack.h

Can someone familiar with NetBSD OpenSSL suggest why some header
files are empty?

Thanks.