Adding gdb-add-index script from Redhat's gdb rpm.

For linux users who are going to debug chromium, running gdb-add-index
on the binary first will significantly speed up debugger start time.

The originating RPM is gdb-7.4.50.20120603-1.1.x86_64.rpm. The script is
just a bash script version of the instructions in the gdb man page.

BUG=none
TEST=ran it on a statically linked browser_tests locally. verfied .gdb_index section exists
and that gdb does startup faster (from ~20 secs to ~3 seconds)

Review URL: https://chromiumcodereview.appspot.com/10695024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@144644 0039d316-1c4b-4281-b951-d872f2087c98

build/gdb-add-index

@@ -0,0 +1,30 @@
+#! /bin/sh
+
+# Add a .gdb_index section to a file.
+
+# Copyright (C) 2010 Free Software Foundation, Inc.
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+file="$1"
+dir="${file%/*}"
+
+# We don't care if gdb gives an error.
+gdb -nx --batch-silent -ex "file $file" -ex "save gdb-index $dir"
+
+if test -f "${file}.gdb-index"; then
+   objcopy --add-section .gdb_index="${file}.gdb-index" --set-section-flags .gdb_index=readonly "$file" "$file"
+   rm -f "${file}.gdb-index"
+fi
+
+exit 0