Cleanups from post-submit suggestions.

build/linux/dump_app_syms

Index: build/linux/dump_app_syms
diff --git a/build/linux/dump_app_syms b/build/linux/dump_app_syms
index 85544be2cbeed467aa539b83bfcadd4940b0d2c2..1ebac5889fce0e0f8e48e9924ff6b83d4b166678 100755
--- a/build/linux/dump_app_syms
+++ b/build/linux/dump_app_syms
@@ -10,7 +10,7 @@
 set -e
 
 usage() {
-  echo "$0 <dump_syms_exe> <binary_with_symbols> <symbols_output>"
+  echo "$0 <dump_syms_exe> <binary_with_symbols> <symbols_output>" >&2
 }
 
 
@@ -26,12 +26,14 @@ OUTFILE="$3"
 
 STRIPPED=$(mktemp -q -t stripped-XXXXX)
 if [ $? -ne 0 ]; then
-  echo "ERROR: Could not create temp stripped '$INFILE'"
+  echo "ERROR: Could not create temp stripped '$INFILE'" >&2
   exit 1
 fi
 
 # Dump the symbols from the given binary.
-"$DUMPSYMS" "$INFILE" > "$OUTFILE"
+if [ "$INFILE" -nt "$OUTFILE" ]; then
+  "$DUMPSYMS" "$INFILE" > "$OUTFILE"
+fi
 
 # Strip the binary and calculate the signature of that, since that's what ships.
 strip "$INFILE" -o "$STRIPPED"
@@ -39,6 +41,4 @@ NEWSIG=$("$SCRIPTDIR/dump_signature.py" "$STRIPPED")
 rm "$STRIPPED"
 
 # Replace the old signature with the stripped signature in the symbols file.
-INFILE_BASE=$(basename "$INFILE")
-sed -i "1s/[0-9A-F]* $INFILE_BASE/$NEWSIG $INFILE_BASE/" "$OUTFILE"
-
+sed -i "1s/ [0-9A-F]* / $NEWSIG /" "$OUTFILE"