i965: fix segfault on low memory conditions
i965: fix segfault on low memory conditions

When out of memory (in at least one case, triggered by a longrunning
memory leak), this code will segfault and crash.  By checking for the
out-of-memory condition, the system can continue, and will report
the out-of-memory error later, a much preferable outcome.

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