* clean up a case where CMake endif()
contained the conditional used in the
if(), which is no longer needed /
discouraged since our minimum required
CMake version supports the modern syntax

(also copy BUNDERSCORE settings for FORTRAN from the corresponding Makefile)

needs to be unset in the cache for the change to have any effect

(and other small fixes to match Makefile behaviour)

Remove any inadvertent use of -march=native from DYNAMIC_ARCH builds

from #2143, -march=native precludes use of more specific options like -march=skylake-avx512 in individual kernels, and defeats the purpose of dynamic arch anyway.

Add gfortran workaround for potential ABI violation

for #2154

21eda8b5 introduced a check in getarch.c to test if the compiler is capable of
AVX512. This check currently fails, since the used __AVX2__ macro is only
defined if getarch itself was compiled with AVX2/AVX512 support. Make sure this
is the case by building getarch with -march=native on x86_64. It is only
supposed to run on the build host anyway.

Found via `codespell -q 3 -w -L ith,als,dum,nd,amin,nto,wis,ba -S ./relapack,./kernel,./lapack-netlib`

Add (C)BLAS extension ?sum

Add -lm and disable EXPRECISION support on *BSD

fixes #2075

for #2056, using same approach as #2058

e.g. cmake -DDYNAMIC_ARCH=1 -DDYNAMIC_LIST="NEHALEM;HASWELL;ZEN" ..
original issue was #1639

Fixed core naming for DYNAMIC_ARCH. Corrected GEMM_DEFAULT entries and added SYMV_P. Replaced outdated VULCAN define for ThunderX2T99 with ARMV8 to get basic definitions back. For issue #1908

Add -mavx2 to TARGET=HASWELL builds

and create config target directory for cross-compiles.

cf #1908

* Handle Android environments that identify as Linux

termux terminal emulator does this, causing build failures through missed defines in common.h

Use KERNEL_DEFINITIONS rather than COMMON_OPTS to pass -march=skylake…

Add -march=skylake-avx512 to CFLAGS when the target is Skylake

Should fix 1806 and #1801

Add -march=skylake-avx512 when required

fixes #1797

Check for Immintrin.h presence in the AVX512 compatibility test as well

Do not treat WIndows UWB builds as cross-compiling

Move some x86_64 DYNAMIC_ARCH targets to new DYNAMIC_OLDER option