Add script to manage gitignore anchors

Added scripts which comment and uncomment out patterns relating to
generated files.

Signed-off-by: Agathiyan Bragadeesh <agabra02@e127300.arm.com>
diff --git a/scripts/gitignore_add_generated_files.sh b/scripts/gitignore_add_generated_files.sh
new file mode 100644
index 0000000..27c3480
--- /dev/null
+++ b/scripts/gitignore_add_generated_files.sh
@@ -0,0 +1,23 @@
+#!/bin/bash
+
+set -eu
+
+GITIGNORES=$(find . -name ".gitignore")
+
+for GITIGNORE in $GITIGNORES; do
+    IN_GEN_BLOCK=false
+    while read -r line; do
+        if [ "$line" = "###START_COMMENTED_GENERATED_FILES###" ]; then
+            IN_GEN_BLOCK=true
+            echo "###START_GENERATED_FILES###"
+        elif [ "$line" = "###END_COMMENTED_GENERATED_FILES###" ]; then
+            IN_GEN_BLOCK=false
+            echo "###END_GENERATED_FILES###"
+        elif $IN_GEN_BLOCK ; then
+            echo "${line:1}"
+        else
+            echo "$line"
+        fi
+    done <$GITIGNORE > "$GITIGNORE.tmp"
+    mv "$GITIGNORE.tmp" $GITIGNORE
+done