This allows us to run/analyze multiple tests.
Also it causes the production code packages to be properly initialized.
Also:
- cmd/ssadump: improved usage message (add example;
incorporate LoadInitialPackages usage; explain how -run
finds main).
- pointer, oracle, ssa/interp: use CreateTestMainPackage.
- ssa/builder.go: remove 'rundefers' instruction from package init,
which no longer uses 'defer'.
R=gri
CC=golang-dev
https://golang.org/cl/15920047
8636f40baf