Fix kelvin_sim for CI

CI machine has less default bazel_tmp storage. Set up the sandbox tmpfs to /tmp
to unblock CI

Change-Id: I6da0e5dbc5b046885b1a1a755ca77f4693ec635f

platforms/nexus/kelvin.mk

diff --git a/platforms/nexus/kelvin.mk b/platforms/nexus/kelvin.mk
index f5dc1be..7e74d2b 100644
--- a/platforms/nexus/kelvin.mk
+++ b/platforms/nexus/kelvin.mk
@@ -48,9 +48,10 @@
 ## Build Kelvin ISS
 #
 # Build mpact-sim-based Kelvin ISS with bazel, and copy it to out/
+# Use /tmp as the bazel tmpfs to unblock CI
 kelvin_sim: | $(KELVIN_SIM_OUT_DIR)
 	cd "$(KELVIN_SIM_SRC_DIR)" && \
-		bazel build //sim:kelvin_sim
+		bazel build --sandbox_tmpfs_path=/tmp //sim:kelvin_sim
 	cd "$(KELVIN_SIM_SRC_DIR)/bazel-bin" && \
 		cp -f sim/kelvin_sim "$(KELVIN_SIM_OUT_DIR)"
 

platforms/shodan/kelvin.mk

diff --git a/platforms/shodan/kelvin.mk b/platforms/shodan/kelvin.mk
index f5dc1be..7e74d2b 100644
--- a/platforms/shodan/kelvin.mk
+++ b/platforms/shodan/kelvin.mk
@@ -48,9 +48,10 @@
 ## Build Kelvin ISS
 #
 # Build mpact-sim-based Kelvin ISS with bazel, and copy it to out/
+# Use /tmp as the bazel tmpfs to unblock CI
 kelvin_sim: | $(KELVIN_SIM_OUT_DIR)
 	cd "$(KELVIN_SIM_SRC_DIR)" && \
-		bazel build //sim:kelvin_sim
+		bazel build --sandbox_tmpfs_path=/tmp //sim:kelvin_sim
 	cd "$(KELVIN_SIM_SRC_DIR)/bazel-bin" && \
 		cp -f sim/kelvin_sim "$(KELVIN_SIM_OUT_DIR)"