WebAssembly: fix build breakage.

Summary:
processFunctionBeforeCalleeSavedScan was renamed to determineCalleeSaves and now takes a BitVector parameter as of rL242165, reviewed in http://reviews.llvm.org/D10909

WebAssembly is still marked as experimental and therefore doesn't build by default. It does, however, grep by default! I notice that processFunctionBeforeCalleeSavedScan is still mentioned in a few comments and error messages, which I also fixed.

Reviewers: qcolombet, sunfish

Subscribers: jfb, dsanders, hfinkel, MatzeB, llvm-commits

Differential Revision: http://reviews.llvm.org/D11199

llvm-svn: 242242