unity build fails if compiz is installed outside /usr

Bug Description

Steps to reproduce the problem:
1. configure compiz (rev 3486) with --prefix=/tmp/staging. make and install it.
2. configure unity with PKG_CONFIG_PATH=/tmp/staging/lib/pkgconfig
3. make unity

Expected outcome:
Unity builds fine

Actual outcome:
linking fails because it cannot find -lcompiz_core.

Comments:
Inspection of the parameters passed to the linker shows that there's no -L/tmp/staging/lib/.

Cause:
line 11 of the file compiz.pc.in ("Libs:") should have -L${libdir}, but that was removed by revision 2993.
Adding it back solves the bug.

What?! Found the same problem trying to build compiz-plugins-main (0.9.7) against compiz-core (0.9.7)

This bug was fixed in the package compiz - 1:0.9.9~daily12.12.05-0ubuntu1

---------------
compiz (1:0.9.9~daily12.12.05-0ubuntu1) raring; urgency=low

[ Michael Terry ]
* debian/control:
- Update Vcs-Bzr
* debian/patches/100_expo_layout.patch:
- Fix to apply
* Automatic snapshot from revision 3451 (bootstrap)
- Fix crash from writing to static memory (LP: #1065814)
- Fix maximized windows changing workspaces (LP: #1071791)
- Respect Zoom Factor setting (LP: #1066187)
- Respect Show Window Title setting (LP: #1009999)
- Restore text background transparency (LP: #1042132)
- Restore screenshot selection rectangle transparency (LP: #1047788)
- Restore top and bottom cube transparency (LP: #1048272)
- Fix scaleaddon window highlighting being solid (LP #1068503)
- Make resize hint overlay disappear when changing edges (LP: #839602)
- Preserve grid IDs during drag (LP: #1067812, LP: #1048855)
- Save current display before doing snap preview (LP: #1068173)
- Ignore inactive keybindings (LP: #1053280)
- Handle <primary> in keyboard shortcuts (LP: #936840)
- Make sure showdesktop plugin is loaded after unityshell (LP: #1067534)
- Fix grid build failure (LP: #1067577)
- Fix Jenkins test failures (LP: #1058577)
- Don't allow duplicate static symbols when linking (LP: #1067964)
- Make external templates C++0x compatible (LP: #1067598)
- Make sure to initialize class members (LP: #1033877)
- Don't duplicate templates in plugins (LP: #1066793, LP: #1066803,
LP: #1066804, LP: #1066805, LP: #1066799, LP: #1066796,
LP: #1066795, LP: #1066798, LP: #1067218, LP: #1067219)
- Don't needlessly set gsettings keys (LP: #1064791)
- Remove unused code (LP: #1037142, LP: #1067234)
- Fix syntax highlighting for trunk xml files (LP: #1066823)
- Fix documentation for building with python2 (LP: #1070211)

[ Stephen M. Webb ]
* Windows open below panel and launcher, grid does not work at all,
window animations missing, and general plugin chaos if built on
raring (cmake >= 2.8.10) (LP: #1085581)

[ Iven Hsu ]
* KDE Appmenu doesn't work with compiz decorators (LP: #1082265)
* compiz 0.9.8.6 fails to build from source in KDE4-window-decorator
with latest KDE 4.10 beta (LP: #1082152)
* kde4-window-decorator crashes when starting up with oxygen theme
(LP: #1050776)

[ sampo555 ]
* Grid: Window management - resize preview does not show when moving a
window from the semi-maximised state to the maximised state in a
single action (LP: #1071689)

[ Timo Jyrinki ]
* HTML5 video in Firefox continues to tear (LP: #1086337)

[ MC Return ]
* Workspacenames Plug-in: Wishlist: Default Appearance values not
ideal (LP: #1075600)
* Resizeinfo Plug-in: No possibility to change the color and
transparency of the rounded background outline (LP: #1070297)
* Resizeinfo Plug-in: Gradient color 2 and 3 settings are ignored and
no background gradient is rendered (LP: #1070233)
* Expo animations "Fade + Zoom" & "Vortex" result in a black screen
(LP: #875311)
* Workspacenames Plug-in: Wishlist: No default values...