gallivm: Return true from arch_rounding_available() if NEON is available

LLVM uses the single instruction "FRINTI" to implement llvm.nearbyint.
Fixes the rounding tests of lp_test_arit.

Bug: https://bugs.gentoo.org/665570
Reviewed-by: Roland Scheidegger <sroland@vmware.com>

src/gallium/auxiliary/gallivm/lp_bld_arit.c

@@ -1992,6 +1992,8 @@ arch_rounding_available(const struct lp_type type)
    else if ((util_cpu_caps.has_altivec &&
             (type.width == 32 && type.length == 4)))
       return TRUE;
+   else if (util_cpu_caps.has_neon)
+      return TRUE;
 
    return FALSE;
 }
@@ -2099,7 +2101,7 @@ lp_build_round_arch(struct lp_build_context *bld,
                     LLVMValueRef a,
                     enum lp_build_round_mode mode)
 {
-   if (util_cpu_caps.has_sse4_1) {
+   if (util_cpu_caps.has_sse4_1 || util_cpu_caps.has_neon) {
       LLVMBuilderRef builder = bld->gallivm->builder;
       const struct lp_type type = bld->type;
       const char *intrinsic_root;

src/gallium/drivers/llvmpipe/lp_test_arit.c

@@ -458,7 +458,8 @@ test_unary(unsigned verbose, FILE *fp, const struct unary_test_t *test, unsigned
             continue;
          }
 
-         if (test->ref == &nearbyintf && length == 2 && 
+         if (!util_cpu_caps.has_neon &&
+             test->ref == &nearbyintf && length == 2 &&
              ref != roundf(testval)) {
             /* FIXME: The generic (non SSE) path in lp_build_iround, which is
              * always taken for length==2 regardless of native round support,