meson: Leave dep_llvm empty if !with_llvm

The gallium auxiliary build would link against llvm, for the gallivm code
that it didn't build.  This broke the build on my armhf cross, where
libLLVM-3.9.so is not multiarch and thus points to x86-64 libs.

Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Tested-by: Timothy Arceri <tarceri@itsqueeze.com>
1 file changed