Android: r600: fix build when LLVM is disabled

Android: r600: fix build when LLVM is disabled

There's still an error after my recent clean-up if LLVM is not patched to
enable AMDGPU target:

external/mesa3d/src/amd/common/ac_llvm_util.c:38:2: error: implicit declaration of function 'LLVMInitializeAMDGPUTargetInfo' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        LLVMInitializeAMDGPUTargetInfo();
        ^
external/mesa3d/src/amd/common/ac_llvm_util.c:39:2: error: implicit declaration of function 'LLVMInitializeAMDGPUTarget' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        LLVMInitializeAMDGPUTarget();
        ^
external/mesa3d/src/amd/common/ac_llvm_util.c:40:2: error: implicit declaration of function 'LLVMInitializeAMDGPUTargetMC' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        LLVMInitializeAMDGPUTargetMC();
        ^
external/mesa3d/src/amd/common/ac_llvm_util.c:41:2: error: implicit declaration of function 'LLVMInitializeAMDGPUAsmPrinter' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        LLVMInitializeAMDGPUAsmPrinter();
        ^

We need to drop libmesa_amd_common when LLVM is disabled, however there's
still a dependency on include paths for ac_binary.h. So explicitly add the
include path when LLVM is disabled.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Nicolai Hähnle <nicolai.haehnle@amd.com>