clover: Don't link against libclangRewrite
clover: Don't link against libclangRewrite

This library does not exist in LLVM 3.2 and libOpenCL.so links fine
without it on LLVM 3.1

Reviewed-by: Francisco Jerez <5906ff32bdd9fd8db196f6ba5ad3afd6f9257ea5@riseup.net>

benaadams/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,wolf96/glsl-optimizer,djreep81/glsl-optimizer,mcanthony/glsl-optimizer,zeux/glsl-optimizer,mapbox/glsl-optimizer,zeux/glsl-optimizer,mapbox/glsl-optimizer,djreep81/glsl-optimizer,zeux/glsl-optimizer,mapbox/glsl-optimizer,zeux/glsl-optimizer,zeux/glsl-optimizer,wolf96/glsl-optimizer,mcanthony/glsl-optimizer,benaadams/glsl-optimizer,dellis1972/glsl-optimizer,zz85/glsl-optimizer,wolf96/glsl-optimizer,dellis1972/glsl-optimizer,mcanthony/glsl-optimizer,mcanthony/glsl-optimizer,jbarczak/glsl-optimizer,bkaradzic/glsl-optimizer,metora/MesaGLSLCompiler,tokyovigilante/glsl-optimizer,jbarczak/glsl-optimizer,mapbox/glsl-optimizer,jbarczak/glsl-optimizer,tokyovigilante/glsl-optimizer,tokyovigilante/glsl-optimizer,tokyovigilante/glsl-optimizer,dellis1972/glsl-optimizer,djreep81/glsl-optimizer,benaadams/glsl-optimizer,zz85/glsl-optimizer,bkaradzic/glsl-optimizer,mcanthony/glsl-optimizer,bkaradzic/glsl-optimizer,bkaradzic/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,metora/MesaGLSLCompiler,dellis1972/glsl-optimizer,benaadams/glsl-optimizer,mapbox/glsl-optimizer,tokyovigilante/glsl-optimizer,zz85/glsl-optimizer,wolf96/glsl-optimizer,zz85/glsl-optimizer,benaadams/glsl-optimizer,wolf96/glsl-optimizer,benaadams/glsl-optimizer,bkaradzic/glsl-optimizer,metora/MesaGLSLCompiler,dellis1972/glsl-optimizer