Compile tinygo benches with -opt=2 -gc=leaking

There's still a large divide with the rust regex bench but this brings
things a bit closer from 32x slower to 19x slower in a quick benchmark.

Author: posborne

benchmarks/tinygo/build.sh

@@ -24,7 +24,7 @@ for dir in */; do
     cd "$dir"
 
     # Build with TinyGo
-    "$TINYGO" build -o "$OUTPUT_DIR/tinygo-$benchmark.wasm" -target=wasi .
+    "$TINYGO" build -o "$OUTPUT_DIR/tinygo-$benchmark.wasm" -target=wasi -opt=2 -gc=leaking .
 
     cd "$SCRIPT_DIR"