Emit instrument-loop in loops.

* am/bootstrap.am (SOURCES):
* module/Makefile.am (SOURCES): Handle renamve of handle-interrupts.scm
  to loop-instrumentation.scm.
* libguile/jit.h (SCM_JIT_COUNTER_ENTRY_INCREMENT): Rename from
  SCM_JIT_COUNTER_CALL_INCREMENT.
* libguile/vm-engine.c (instrument-entry): Rename from instrument-call.
* module/language/cps/compile-bytecode.scm (compile-function): Add
  handle-interrupts code before calls and returns.  Compile the
  "instrument-loop" primcall to an "instrument-loop" instruction and a
  "handle-interrupts" instruction.
  (lower-cps): Adapt to add-loop-instrumentation name change.
* module/language/cps/loop-instrumentation.scm: Rename from
  handle-interrupts.scm and just add "instrument-loop" primcalls in
  loops.  The compiler will add handle-interrupts primcalls as
  appropriate.
* module/system/vm/assembler.scm (<jit-data>): New data type, for
  emitting embedded JIT data.
  (<meta>): Add field for current JIT data.
  (make-meta): Initialize current JIT data.
  (emit-instrument-entry*, emit-instrument-loop*): New instruction
  emitters that reference the current JIT data.
  (end-program): Now that all labels are known, arrange to serialize the
  JIT data.
  (link-data): Reserve space for JIT data, and add relocs to initialize
  the "start" / "end" fields.

am/bootstrap.am

@@ -81,8 +81,8 @@ SOURCES =					\
   language/cps/dce.scm				\
   language/cps/devirtualize-integers.scm	\
   language/cps/effects-analysis.scm		\
-  language/cps/handle-interrupts.scm		\
   language/cps/licm.scm				\
+  language/cps/loop-instrumentation.scm		\
   language/cps/peel-loops.scm			\
   language/cps/prune-top-level-scopes.scm	\
   language/cps/reify-primitives.scm		\