for indefinitely repeating error messages "Did not find expire comment
in rules list 0" in rule deletion code, and the second where min_exp
was not computed correctly for min_exp equal to zero. See github issue #295.

add ALLOW_ANY_USER_AGENT to ignore incoming User-Agent strings in SPA packets over HTTP, closes #296

khorben/coverity/1355235 TOCTOU

This should help fwknop remain as portable as before.
The fallback code still suffers from the TOCTOU condition though.

This also needs fileno() after fopen(). This time it addresses the code
for the client.

This is the third part of three for Coverity issue 1355235.

This also needs fileno() after fopen().

This is the second part of three for Coverity issue 1355235.

This is the first part of three for Coverity issue 1355235.

Replace strlcpy() with memcpy() since the source buffer is not a string.
strlcpy() caught this anyway, but memcpy() usage is probably more valid.

==29766==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x562bc2e50420 in strlcpy /home/mbr/git/fwknop.git/common/strlcpy.c:61:3
    #1 0x562bc2e25362 in process_packet /home/mbr/git/fwknop.git/server/process_packet.c:225:5
    #2 0x7fa6173c9d57  (/lib64/libpcap.so.1+0x1fd57)
    #3 0x562bc2e2456a in pcap_capture /home/mbr/git/fwknop.git/server/pcap_capture.c:227:15
    #4 0x562bc2e13ef0 in main /home/mbr/git/fwknop.git/server/fwknopd.c:296:13
    #5 0x7fa61643724a in __libc_start_main /usr/src/debug/glibc-2.27-74-g68c1bf8097/csu/../csu/libc-start.c:308:16
    #6 0x562bc2d9dec9 in _start (/home/mbr/git/fwknop.git/server/.libs/fwknopd+0x1dec9)

  Uninitialized value was created by a heap allocation
    #0 0x562bc2da6c84 in malloc (/home/mbr/git/fwknop.git/server/.libs/fwknopd+0x26c84)
    #1 0x7fa6173ca996  (/lib64/libpcap.so.1+0x20996)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /home/mbr/git/fwknop.git/common/strlcpy.c:61:3 in strlcpy

utils.c:217:13: warning: variable 'i' is incremented both in the loop header and in the loop
      body [-Wfor-loop-analysis]
            i++;
            ^
utils.c:213:34: note: incremented here
        for (i=0; i<strlen(str); i++)

[server] fix UBSAN warning 'fwknopd.c:1044:50: runtime error: left shift of 2 by 30 places cannot be represented in type 'int''

[test suite] start with -m32 gcc option for ASAN instrumentation check (32-bit compilation is preferred for ASAN operations)