make hello world simd a bit cleaner (#701)

bazel/hello-world/BUILD

diff --git a/bazel/hello-world/BUILD b/bazel/hello-world/BUILD
index 1c7e087..07fbed5 100644
--- a/bazel/hello-world/BUILD
+++ b/bazel/hello-world/BUILD
@@ -19,4 +19,5 @@
 wasm_cc_binary(
     name = "hello-world-wasm-simd",
     cc_target = ":hello-world-simd",
+    simd = True,
 )

scripts/test_bazel.sh

diff --git a/scripts/test_bazel.sh b/scripts/test_bazel.sh
index 4194ad7..6a2c98d 100755
--- a/scripts/test_bazel.sh
+++ b/scripts/test_bazel.sh
@@ -22,4 +22,4 @@
 
 cd bazel
 bazel build //hello-world:hello-world-wasm
-bazel build --copt="-msimd128" //hello-world:hello-world-wasm-simd
+bazel build //hello-world:hello-world-wasm-simd