tools/run: Remove 'bin' cache

People keep on running the executable from the bin cache, wondering why stuff is out of date.

`go run` has pretty decent builtin caching, so just use that.

Change-Id: I6305a222f3f6b5b0b1ce23d7a89227aea96b9ef4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/118720
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Ben Clayton <bclayton@google.com>
Auto-Submit: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>

.gitignore

@@ -33,7 +33,6 @@
 /third_party/vulkan_memory_allocator
 /third_party/webgpu-cts
 /third_party/zlib
-/tools/bin
 /tools/clang
 /tools/cmake*
 /tools/golang

tools/run

@@ -17,7 +17,6 @@ set -e # Fail on any error.
 
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd )"
 TOOL="$1"
-BINARY="${SCRIPT_DIR}/bin/${TOOL}"
 
 if [ ! -x "$(which go)" ] ; then
   echo "error: go needs to be on \$PATH to use $0"
@@ -46,10 +45,6 @@ if [ ! -d "${SCRIPT_DIR}/src/cmd/${TOOL}" ]; then
   show_usage
 fi
 
-# Rebuild the binary.
-# Note, go caches build artifacts, so this is quick for repeat calls
 pushd "${SCRIPT_DIR}/src" > /dev/null
-    go build -o "${BINARY}" "./cmd/${TOOL}"
+    go run "./cmd/${TOOL}" "${@:2}"
 popd > /dev/null
-
-"${BINARY}" "${@:2}"