configure: error out when building static XOR shared
configure: error out when building static XOR shared

Current code warns out in such cases and falls-back to either static or
shared. That can be easily missed amongst the volume produced by our
configure script.

Replace the warning with an error such that one gets direct feedback
when they're doing something wrong.

Signed-off-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler