gallivm: Remove LLVMOpaqueKindType case with llvm-3.0.

llvm-3.0svn r134829 removed LLVMOpaqueKindType from enum LLVMTypeKind in
include/llvm-c/Core.h.

src/gallium/auxiliary/gallivm/lp_bld_type.c

@@ -325,8 +325,10 @@ lp_typekind_name(LLVMTypeKind t)
       return "LLVMArrayTypeKind";
    case LLVMPointerTypeKind:
       return "LLVMPointerTypeKind";
+#if HAVE_LLVM < 0x0300
    case LLVMOpaqueTypeKind:
       return "LLVMOpaqueTypeKind";
+#endif
    case LLVMVectorTypeKind:
       return "LLVMVectorTypeKind";
    case LLVMMetadataTypeKind: