pkg/52298: pkgtools/pkg_install fails to build with OpenSSL 1.1.0 due to incomplete type in check_ca()

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>Number:         52298
>Category:       pkg
>Synopsis:       pkgtools/pkg_install fails to build with OpenSSL 1.1.0 due to incomplete type in check_ca()
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jun 14 01:35:00 +0000 2017
>Originator:     Sevan Janiyan
>Release:        pkgsrc-current
>Organization:
>Environment:
Linux pkgsrc 4.9.0-3-amd64 #1 SMP Debian 4.9.30-1 (2017-06-04) x86_64 GNU/Linux

>Description:
On Debian 9.0 with OpenSSL 1.1.0f install, attempting to bootstrap pkgsrc fails with the following error

cc -DHAVE_CONFIG_H -DDEF_LOG_DIR=\"/usr/pbulk/pkgdb\" -D_LARGEFILE_SOURCE -D_LARGE_FILES -D_FILE_OFFSET_BITS=64 -DDEF_UMASK=022 -I/tmp/work-pbulk/wrk/pkgtools/pkg_install/work/bzip2 -I/tmp/work-
pbulk/wrk/pkgtools/pkg_install/work/libarchive/libarchive -I/tmp/work-pbulk/wrk/pkgtools/pkg_install/work/libfetch -I/tmp/work-pbulk/wrk/pkgtools/pkg_install/work -DHAVE_NBCOMPAT_H=1 -I/tmp/work
-pbulk/wrk/pkgtools/pkg_install/work/libnbcompat -I/usr/include -I. -I. -DSYSCONFDIR=\"/usr/pbulk/etc\" -DHAVE_SSL -O2 -I/usr/include -c pkcs7.c
pkcs7.c: In function 'check_ca':
pkcs7.c:63:11: error: dereferencing pointer to incomplete type 'X509 {aka struct x509_st}'
  if ((cert->ex_flags & EXFLAG_KUSAGE) != 0 &&
           ^~
*** [pkcs7.o] Error code 1

bmake[1]: stopped in /tmp/work-pbulk/wrk/pkgtools/pkg_install/work/pkg_install-20170419/lib

>How-To-Repeat:

>Fix: