Simplify cmake option handling by putting everything in blocks.

Add openssl patch as there's no easy way to disable.

Rebase the skip manpages patch.

Remove the monitor mode patch as it no longer applies.

Remove flex patch as normal Makefile is no longer used.

Remove USB path patch. While it is deprecated, the codepath is never
taken. /sys/bus/usb/devices is checked before hand. If it exists, the
function does stuff and returns. Additionally, this path is used
elsewhere in the code.

Refresh other patches.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

The main motivation is to drop and stop maintaining
"100-debian_shared_lib.patch".  It lacks the logic to include custom
implementation of several functions like pcap_strlcpy() which can cause
build failures when glibc is used [2]

CAN and CAN-USB support related symbols are now handled by general linux
support, see [1]

"-ffunction-sections -fdata-sections" were removed as they should help
much for shared libraries

Size comparison before and after the change

  -rw-r--r-- 1 yunion yunion 238042 Oct 18 11:42 ipkg-x86_64/libpcap/usr/lib/libpcap.so.1

  lrwxrwxrwx 1 yunion yunion     16 Oct 18 13:03 ipkg-x86_64/libpcap/usr/lib/libpcap.so.1 -> libpcap.so.1.9.1
  -rwxr-xr-x 1 yunion yunion 229867 Oct 18 13:03 ipkg-x86_64/libpcap/usr/lib/libpcap.so.1.9.1

[1] On Linux, handle all CAN captures with pcap-linux.c, in cooked mode,
    https://github.com/the-tcpdump-group/libpcap/commit/93ca5ff7030aaf1219e1de05ec89a68384bfc50b
[2] https://github.com/openwrt/packages/issues/10270



Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>