test: set common.bits to 64 for riscv64

PR-URL: #38626
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/common/index.js

@@ -34,7 +34,7 @@ const util = require('util');
 const { isMainThread } = require('worker_threads');
 
 const tmpdir = require('./tmpdir');
-const bits = ['arm64', 'mips', 'mipsel', 'ppc64', 's390x', 'x64']
+const bits = ['arm64', 'mips', 'mipsel', 'ppc64', 'riscv64', 's390x', 'x64']
   .includes(process.arch) ? 64 : 32;
 const hasIntl = !!process.config.variables.v8_enable_i18n_support;