Revert 183957

Revert 183957
> pkg-config-wrapper shouldn't clobber PKG_CONFIG_PATH if it is already set
> 
> This allows cross-compilation using sysroots with pkgconfig directories in
> non-standard locations.
> 
> Add Opera Software to the AUTHORS file
> 
> 
> BUG=
> 
> 
> Review URL: https://chromiumcodereview.appspot.com/12320047

TBR=mostynb@opera.com
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=184008

[calvinlo, 2013-02-22 03:57:48]

Committed patchset #1 manually as r184008.

[calvinlo, 2013-02-22 04:04:27]

On 2013/02/22 03:57:48, calvinlo wrote:
> Committed patchset #1 manually as r184008.

I think this might have caused a breakage on ChromeOS buildbots. 
http://build.chromium.org/p/chromium.chromiumos/builders/ChromiumOS%20%28amd6...

The log indicates:
chromeos-chrome-27.0.1420.0_alpha-r1: Updating projects from gyp files...
chromeos-chrome-27.0.1420.0_alpha-r1: Package libcras was not found in the
pkg-config search path.
chromeos-chrome-27.0.1420.0_alpha-r1: Perhaps you should add the directory
containing `libcras.pc'
chromeos-chrome-27.0.1420.0_alpha-r1: to the PKG_CONFIG_PATH environment
variable
chromeos-chrome-27.0.1420.0_alpha-r1: No package 'libcras' found

[Mostyn Bramley-Moore, 2013-02-22 07:11:53]

Does the build environment have PKG_CONFIG_PATH set?  If so, what is it set to? 
Should it be unset?

[calvinlo, 2013-02-22 07:14:13]

I'm honestly not sure, I'm just sheriffing to keep the tree green. Please try
asking in IRC channel or one of the existing authors.