configure.in: Properly detect platform for SSE2 instructions.

* configure.in: add qouting brackets and append wildcard for the
  rest after target_cpu, to properly detect platform for SSE2
  instructions.  [ruby-core:60576] [Bug #8358]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44890 b2dd03c8-39d4-4d8f-98ff-823fe69b080e