Fix some tests in -Asserts mode.

 - FileCheck is a *huuuuge* improvement here.

 - Still feels like we could use a better tool for this though, either teach
   llvm-dis to spit out the FileCheck syntax, or provide another tool to turn a
   .ll into a "matchable" input.

 - Also on my Christmas list is better FileCheck diagnostics with missing
   variables or mismatches.

llvm-svn: 86800