Make gdb-add-index better respect relative paths and bind mounts

Make gdb-add-index better respect relative paths and bind mounts.

Without this, gdb-add-index incorrectly skips DSO dependencies if running from a symlink.  $(pwd) returns the path to your directory via the symlink, but ldd returns the "realpath".  Using dirname allows you to match a substring of the path returned by ldd.

BUG=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=156968

[awong, 2012-09-14 06:39:09]

Without this, gdb-add-index incorrectly scripts DSO dependencies if you use
--bind mount of the output directory.

[Nico, 2012-09-14 06:47:12]

On 2012/09/14 06:39:09, awong wrote:
> Without this, gdb-add-index incorrectly scripts DSO dependencies if you use
> --bind mount of the output directory.

^ Move to CL description.

<noideadog>LGTM stamp</noideadog>

[commit-bot: I haz the power, 2012-09-14 07:04:15]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ajwong@chromium.org/10913264/1

[awong, 2012-09-14 07:06:05]

Example:

ajwong@ajwong-linux:~/src/chromium/src$ ldd out/Debug/browser_tests
	linux-vdso.so.1 =>  (0x00007fffea5ff000)
	libui.so => /usr/local/data/chromium/src/out/Debug/lib/libui.so
(0x00007fed3a4e4000)
	libgles2_c_lib.so =>
/usr/local/data/chromium/src/out/Debug/lib/libgles2_c_lib.so
(0x00007fed3a4ad000)
         <snip>

Actually, it's not mount-bind, it's symlinks.  ~/src/chromium/src is a symlink
to /usr/local/data/chromium/src, and ldd resolves to the real path.  Thus, the
grep using $(pwd) incorrectly filters these out.

[commit-bot: I haz the power, 2012-09-14 17:42:27]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ajwong@chromium.org/10913264/1

[commit-bot: I haz the power, 2012-09-14 22:47:18]

Sorry for I got bad news for ya.
Compile failed with a clobber build.
Your code is likely broken or HEAD is junk. Please ensure your
code is not broken then alert the build sheriffs.
Look at the try server FAQ for more details.

[commit-bot: I haz the power, 2012-09-15 01:26:52]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ajwong@chromium.org/10913264/1

[commit-bot: I haz the power, 2012-09-15 02:28:21]

Change committed as 156968