glsl: fix segfault when indirect indexing a buffer variable which is an array
glsl: fix segfault when indirect indexing a buffer variable which is an array

Fixes a regression added by bb5aeb854915ba67abc56257f830d002c956439e.

Signed-off-by: Samuel Iglesias Gonsalvez <b753b212f30aed827c3eea2e437609dc37310153@igalia.com>
Reviewed-by: Timothy Arceri <7f85c8176b2576ffafd04ac63cd29ed35ff86cb6@yahoo.com.au>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler