radeonsi: drop support for LLVM 3.8

LLVM 3.8:
- had broken indirect resource indexing
- didn't have scratch coalescing
- was the last user of problematic v16i8
- only supported OpenGL 4.1

This leaves us with LLVM 3.9 and LLVM 4.0 support for Mesa 17.2.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/amd/common/ac_llvm_util.c

@@ -105,17 +105,10 @@ static const char *ac_get_llvm_processor_name(enum radeon_family family)
 		return "fiji";
 	case CHIP_STONEY:
 		return "stoney";
-#if HAVE_LLVM == 0x0308
-	case CHIP_POLARIS10:
-		return "tonga";
-	case CHIP_POLARIS11:
-		return "tonga";
-#else
 	case CHIP_POLARIS10:
 		return "polaris10";
 	case CHIP_POLARIS11:
 		return "polaris11";
-#endif
 	default:
 		return "";
 	}