Fix checksum verification

The current approach was prone to spurious failures when `perl` feels chatty, e.g.:

```
$ shasum -a 256 openssl-3.4.0.tar.gz
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LC_ALL = (unset),
        LANG = "en_XX.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
e15dda82fe2fe8139dc2ac21a36d4ca01d5313c75f99f46c4e8a27709b7294bf  openssl-3.4.0.tar.gz
```

Instead, verify the checksum file directly.

scripts/build.sh

@@ -23,13 +23,8 @@ if [[ ! -f "${BUILD_ROOT_DIR}/openssl-${OPENSSL_VERSION}.tar.gz" ]]; then
   echo "Downloading openssl-${OPENSSL_VERSION}.tar.gz"
   curl -fL "https://github.com/openssl/openssl/releases/download/openssl-${OPENSSL_VERSION}/openssl-${OPENSSL_VERSION}.tar.gz" -o "${BUILD_ROOT_DIR}/openssl-${OPENSSL_VERSION}.tar.gz"
   curl -fL "https://github.com/openssl/openssl/releases/download/openssl-${OPENSSL_VERSION}/openssl-${OPENSSL_VERSION}.tar.gz.sha256" -o "${BUILD_ROOT_DIR}/openssl-${OPENSSL_VERSION}.tar.gz.sha256"
-  DIGEST=$( cat "${BUILD_ROOT_DIR}/openssl-${OPENSSL_VERSION}.tar.gz.sha256" )
 
-  if [[ "$(shasum -a 256 "${BUILD_ROOT_DIR}/openssl-${OPENSSL_VERSION}.tar.gz" | awk '{ print " "$1}')" != "${DIGEST}" ]]
-  then
-    echo "openssl-${OPENSSL_VERSION}.tar.gz: checksum mismatch"
-    exit 1
-  fi
+  sha256sum --strict --check "${BUILD_ROOT_DIR}/openssl-${OPENSSL_VERSION}.tar.gz.sha256"
   rm -f "${BUILD_ROOT_DIR}/openssl-${OPENSSL_VERSION}.tar.gz.sha256"
 fi