Run valgrind without march=native

Valgrind doesn't always support all relevant instructions and crashes
on some platforms, most notably github CI.

tests/test.sh

@@ -59,7 +59,7 @@ make clean;  make test CFLAGS="-DBLAKE2_NO_UNROLLING -O3"
 make clean;  make test CC="clang -std=c99" CFLAGS="-g -fsanitize=address"
 make clean;  make test CC="clang -std=c99" CFLAGS="-g -fsanitize=memory"
 make clean;  make test CC="clang -std=c99" CFLAGS="-g -fsanitize=undefined"
-make clean;  make test.out;  valgrind ./test.out
+make clean;  make test.out; CFLAGS="-g"  valgrind ./test.out
 
 echo
 echo "All sanitisers passed!"