Fix TOTAL_MEMORY usage in benchmarks (#9273)

Broken by #9207.

Author: quantum5

tests/test_benchmark.py

@@ -190,7 +190,7 @@ def build(self, parent, filename, args, shared_args, emcc_args, native_args, nat
     cmd = [
       PYTHON, EMCC, filename,
       OPTIMIZATIONS,
-      '-s', 'TOTAL_MEMORY=256*1024*1024',
+      '-s', 'TOTAL_MEMORY=256MB',
       '-s', 'FILESYSTEM=0',
       '--closure', '1',
       '-s', 'MINIMAL_RUNTIME=0',