Rearrange serialization block order to put decl update emission into the same
block as decl and type emission. This allows decl updates include statements
and expressions. No functionality change (but the generated PCM files are
incompatible with earlier versions of Clang).
PGO: Add function to reset counters at runtime

Adding __llvm_pgo_reset_counters(), which sets all the counters to 0.

<rdar://problem/15943240>
Add vim swap files to .gitignore