Accounting for gcc requiring explicit -latomic in bootstrap.sh

On some architectures rograms which use C11 or C++11 atomics,
like #include <atomic>, generally must link against -latomic
explicitly.

For now the check is only against riscv64, but the list may grow.

Signed-off-by: Roman Shaposhnik <rvs@zededa.com>
8 jobs for !1 with work in 10 minutes and 34 seconds (queued for 15 seconds)
detached
Status Job ID Name Coverage
  Lint
passed lint #406163
docker-alpine x86_64

00:03:54

 
  Build
passed build-aarch64 #406168
docker-alpine ci-build aarch64

00:04:28

passed build-armhf #406170
docker-alpine ci-build armhf

00:04:59

passed build-armv7 #406169
docker-alpine ci-build armv7

00:04:49

passed build-ppc64le #406167
docker-alpine ci-build ppc64le

00:06:39

passed build-s390x #406166
docker-alpine ci-build s390x

00:04:19

passed build-x86 #406165
docker-alpine ci-build x86

00:03:36

passed build-x86_64 #406164
docker-alpine ci-build x86_64

00:03:22