pa: build.sh: propogate mka return code

This requires https://gerrit.aospa.co/#/c/3692/

As in the associated commit, this change propogates the return code to
the shell environment which called the script. It also prints "Build
Failed!" in red as an indication to the user that the build has failed.

Change-Id: Ifedffecf4bf87f908056779e5e26e8f997998872
Signed-off-by: Evan Anderson <evananderson@aospa.co>

build.sh

@@ -152,6 +152,8 @@ fi
 echo -e ""
 
 # Build away!
+RETVAL=0
+
 echo -e "${CLR_BLD_BLU}Starting compilation${CLR_RST}"
 echo -e ""
 if [ "$FLAG_USER_BUILD" = 'y' ]; then
@@ -159,11 +161,20 @@ if [ "$FLAG_USER_BUILD" = 'y' ]; then
 else
         mka bacon
 fi
+RETVAL=$?
 echo -e ""
 
+# Check if the build failed
+if [ $RETVAL -ne 0 ]; then
+        echo "${CLR_BLD_RED}Build failed!"
+        echo -e ""
+fi
+
 # Check the finishing time
 TIME_END=$(date +%s.%N)
 
 # Log those times at the end as a fun fact of the day
 echo -e "${CLR_BLD_GRN}Total time elapsed:${CLR_RST} ${CLR_GRN}$(echo "($TIME_END - $TIME_START) / 60" | bc) minutes ($(echo "$TIME_END - $TIME_START" | bc) seconds)${CLR_RST}"
 echo -e ""
+
+exit $RETVAL