src: make Suricata build on Solaris

[l1gi]

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• [X] I have read the contributing guide lines at https://docs.suricata.io/en/latest/devguide/contributing/contribution-process.html
• [X] I have signed the Open Information Security Foundation contribution agreement at https://suricata.io/about/contribution-agreement/ (note: this is only required once)
• [X] I have updated the user guide (in doc/userguide/) to reflect the changes made (if applicable)
• [X] I have created a ticket at https://redmine.openinfosecfoundation.org/projects/suricata/issues (if applicable)

Link to ticket: https://redmine.openinfosecfoundation.org/issues/7005

Describe changes:

• src/main.c: Fix alignment problems on SPARC. Based on similar fixes found at: https://lists.debian.org/debian-sparc/2012/01/msg00012.html and: https://www.winehq.org/pipermail/wine-patches/2011-February/098547.html
• src/source-pcap-file-directory-helper.c, src/util-path.c: Solaris doesn't define d_type dirent member and DT_REG type.
• src/suricata.c: Only Linux and the BSDs support the RLIMIT_NPROC resource limit.
• src/util-syslog.c: Solaris syslog.h doesn't define LOG_FTP.
• src/util-time.c: Solaris tm doesn't define tm_gmtoff member.