[debugger] Use correct archiver

This will allow usage of emscripten 1.39.6 to build

Change-Id: I089f47fa4fa38bf55c5071f5d711856c8ab422b8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/267080
Reviewed-by: Kevin Lubick <kjlubick@google.com>

experimental/wasm-skp-debugger/compile.sh

@@ -20,6 +20,7 @@ pushd $BASE_DIR/../..
 source $EMSDK/emsdk_env.sh
 EMCC=`which emcc`
 EMCXX=`which em++`
+EMAR=`which emar`
 
 if [[ $@ == *debug* ]]; then
   echo "Building a Debug build"
@@ -65,6 +66,7 @@ echo "Compiling bitcode"
 ./bin/gn gen ${BUILD_DIR} \
   --args="cc=\"${EMCC}\" \
   cxx=\"${EMCXX}\" \
+  ar=\"${EMAR}\" \
   extra_cflags_cc=[\"-frtti\"] \
   extra_cflags=[\"-s\", \"WARN_UNALIGNED=1\", \"-s\", \"MAIN_MODULE=1\",
     \"-DSKNX_NO_SIMD\", \"-DSK_DISABLE_AAA\",