tests/meson.build: disable nouveau tests for static build

Signed-off-by: Peter Seiderer ps.report@gmx.net

Notes:

• the existing test/check for static build in meson.build does not catch this case because e.g. the buildroot toolchain br-arm-full-static-2019.05.1 provides an empty libdl.a

169 # Among others FreeBSD does not have a separate dl library. 170 if not cc.has_function('dlsym') 171 dep_dl = cc.find_library('dl', required : with_nouveau) 172 else 173 dep_dl = [] 174 endif