Add a target that yells at you if your sdkconfig is out of date

tools/cmake/check-for-sdkconfig-changes.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+SDKCONFIG=$PROJ_PATH/sdkconfig
+SDKCONFIG_COMMON=$PROJ_PATH/sdkconfig.common
+if [ ! -f "$SDKCONFIG" ]; then
+  exit 0
+fi
+if [ "$SDKCONFIG" -nt "$SDKCONFIG_COMMON" ]; then
+  exit 0
+fi
+RED='\033[0;31m'
+NOCOLOUR='\033[0m'
+echo -e "$RED########################################################################$NOCOLOUR"
+echo "'sdkconfig.common' is newer than 'sdkconfig'! You may be building with"
+echo "an out of date configuration. Delete your 'sdkconfig' to refresh your"
+echo "build configuration, or 'touch sdkconfig' to silence this warning."
+echo -e "$RED########################################################################$NOCOLOUR"
+exit 1