Do not use `realpath` to get absolute paths

There are two reasons to avoid using `realpath` in our scripts:
(a) It resolves symlinks by default. This can be avoided with a flag.
(b) It is not installed by default on some Linux distros.
Use the `$(cd <dir> && pwd)` trick instead.

This is necessary for checking out Hafnium using repo.

Change-Id: I5dd11d91a55054728723648e5c4192f8f1095b6b
diff --git a/build/run_in_container.sh b/build/run_in_container.sh
index cfb8629..4090c38 100755
--- a/build/run_in_container.sh
+++ b/build/run_in_container.sh
@@ -14,8 +14,8 @@
 # limitations under the License.
 set -euo pipefail
 
-SCRIPT_DIR="$(realpath "$(dirname "${BASH_SOURCE[0]}")")"
-ROOT_DIR="$(realpath ${SCRIPT_DIR}/..)"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT_DIR="$(dirname ${SCRIPT_DIR})"
 
 source "${SCRIPT_DIR}/docker/common.inc"
 
@@ -114,4 +114,4 @@
 ${DOCKER} run \
 	${ARGS[@]} \
 	"${IMAGE_ID}" \
-	/bin/bash -c "$*"
\ No newline at end of file
+	/bin/bash -c "$*"