pipebuffer: avoid assert due to increasing a zeroed refcnt
pipebuffer: avoid assert due to increasing a zeroed refcnt

The cache manager stores buffers with a reference count that dropped to 0.
pipe_reference asserts in this case on debug builds,
so use pipe_reference_init instead.

Signed-off-by: José Fonseca <61b5a29db2c0650f7c8510f93eece059c1b09320@vmware.com>

benaadams/glsl-optimizer,mcanthony/glsl-optimizer,zeux/glsl-optimizer,dellis1972/glsl-optimizer,tokyovigilante/glsl-optimizer,wolf96/glsl-optimizer,zeux/glsl-optimizer,mapbox/glsl-optimizer,mcanthony/glsl-optimizer,djreep81/glsl-optimizer,mcanthony/glsl-optimizer,mapbox/glsl-optimizer,dellis1972/glsl-optimizer,wolf96/glsl-optimizer,adobe/glsl2agal,adobe/glsl2agal,mapbox/glsl-optimizer,zz85/glsl-optimizer,zeux/glsl-optimizer,metora/MesaGLSLCompiler,KTXSoftware/glsl2agal,bkaradzic/glsl-optimizer,bkaradzic/glsl-optimizer,KTXSoftware/glsl2agal,zz85/glsl-optimizer,bkaradzic/glsl-optimizer,zeux/glsl-optimizer,jbarczak/glsl-optimizer,benaadams/glsl-optimizer,djreep81/glsl-optimizer,tokyovigilante/glsl-optimizer,adobe/glsl2agal,jbarczak/glsl-optimizer,zz85/glsl-optimizer,jbarczak/glsl-optimizer,wolf96/glsl-optimizer,metora/MesaGLSLCompiler,benaadams/glsl-optimizer,dellis1972/glsl-optimizer,mapbox/glsl-optimizer,tokyovigilante/glsl-optimizer,tokyovigilante/glsl-optimizer,adobe/glsl2agal,dellis1972/glsl-optimizer,metora/MesaGLSLCompiler,benaadams/glsl-optimizer,wolf96/glsl-optimizer,zz85/glsl-optimizer,wolf96/glsl-optimizer,bkaradzic/glsl-optimizer,zz85/glsl-optimizer,KTXSoftware/glsl2agal,djreep81/glsl-optimizer,mapbox/glsl-optimizer,zeux/glsl-optimizer,mcanthony/glsl-optimizer,mcanthony/glsl-optimizer,benaadams/glsl-optimizer,benaadams/glsl-optimizer,tokyovigilante/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,adobe/glsl2agal,dellis1972/glsl-optimizer,KTXSoftware/glsl2agal,djreep81/glsl-optimizer,jbarczak/glsl-optimizer,KTXSoftware/glsl2agal,bkaradzic/glsl-optimizer,jbarczak/glsl-optimizer