make : improve cpuinfo handling on x86 hosts (#1238)

make : improve cpuinfo handling on x86 hosts (#1238)

* make : simplify and correct x86 ISA extensions detection on the host

It got broken in commit c5f9acf4b797 for Haiku and Mac OS (Intel),
which report CPU features in upper case.

Now we're finding the names in case-insensitive manner and as words.
SSE3 detection has been corrected for Linux, which uses PNI for that
(Prescott New Instructions).

* make : use dmesg.boot in FreeBSD/DragonFlyBSD to detect x86 ISA extensions on the host

* make : enable x86 ISA extensions on the host both in CFLAGS and CXXFLAGS

* make : correct AVX x86 ISA extension detection on macOS (Intel) host

It got broken in commit c5f9acf4b797.  macOS calls it AVX1.0.