mesa: use correct return statement for a void function
mesa: use correct return statement for a void function

Using return foo() is incorrect even if foo itself returns void.
Spotted by AppVeyor, as below:

teximage.c(3653) : warning C4098: 'copyteximage' : 'void' function returning a value

Signed-off-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>
Reviewed-by: Nicolai Hähnle <0d0be6cf5ad662651be2dc5dfd44aa2b09d4c1cc@amd.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler