Run the stack calibration script before running the compiler.

Run the stack calibration script before running the compiler.

* am/guilec (.scm.go): Use `pre-inst-guile' and load
  `stack-limit-calibration.scm'.  This is particularly useful when
  building the first `.go' files where the compiler is run using the
  interpreter, which may end up using a lot of stack space.

* libguile/Makefile.am (BUILT_SOURCES): Add
  `stack-limit-calibration.scm'.
  (TESTS, TESTS_ENVIRONMENT): Remove.
  (stack-limit-calibration.scm): Prepend `-' so that any errors during
  the calibration are ignored.