main/zstd: fix build on armhf

For armhf, we pass `-DMEM_FORCE_MEMORY_ACCESS=0` to make to prevent a
bus error during build. When running `make check`, it builds the project
again, but now without the flags specified in the `build()` function.

Although it's undesired that `make check` builds the project again, it's
unclear why this happens.

To prevent the bus error in the check phase, make sure the same flags
are provided.
7 jobs for !19462 with zstd-fix-check-armhf in 3 minutes and 12 seconds
detached
Status Job ID Name Coverage
  Lint
passed #349075
docker-alpine x86_64
lint

00:00:18

 
  Build
passed #349080
docker-alpine ci-build aarch64
build-aarch64

00:02:10

passed #349081
docker-alpine ci-build armv7
build-armv7

00:02:27

passed #349079
docker-alpine ci-build ppc64le
build-ppc64le

00:02:51

passed #349078
docker-alpine ci-build s390x
build-s390x

00:02:05

passed #349077
docker-alpine ci-build x86
build-x86

00:01:23

passed #349076
docker-alpine ci-build x86_64
build-x86_64

00:01:16