anv: fix hang during generation of dev_icd.json.
anv: fix hang during generation of dev_icd.json.

Fixes: b370ec7c76d ("anv: tweak the %.json rule")
Reviewed-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler