child_process: remove unreachable execSync() code

[cjihrig]

Checklist

• make -j8 test (UNIX), or vcbuild test nosign (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

child_process

Description of change

Code coverage showed that the execSync() variable inheritStderr was never set to the default value of true. This is because the default case is hit whenever normalizeExecArgs() returns an object without an options property. However, this can never be the case because normalizeExecArgs() unconditionally creates the options object. This commit removes the unreachable code.