Recover full backtraces with generic arithmetic on x86 and x86-64

 * Errors in generic arithmetic (or comparisons) used to hide the caller
   in the backtrace: it was replaced with a frame in the anonymous
   assembly stub.

 * Regression since 1.0.24.35, fixes lp#800343.

 * Also remove a misleading FIXME in typed-accessor-definitions
   (reported by Matt Novenstern in lp#1171646).
COMPILE-FILE shouldn't "attempt to dump invalid structure" anymore

 * When CAST nodes detect definite type mismatch, they are replaced
   with debugging instrumentation to provide source locations at
   compile and run -time. When code is generated internally, the
   source can include literal internal data structures. Skip those
   when recovering source locations.

 * Fixes lp#943953 and a bunch of equally baffling duplicates.
More robust erroneous local call detection

 * When possible, convert known bad calls into calls to error-signaling
   stubs.

 * Fixes lp#504121 (and likely other occurrences of
   "failed AVER (ZEROP (HASH-TABLE-COUNT ...))."
Insert typechecks before RAW-INSTANCE-INIT in structure constructors

 * Usually, FTYPE declarations ensure that happens, but multiple
   inlining of the same structure constructor cause strangeness.

 * Fixed lp#1177703, reported by Jan Moringen.
More efficient MASK-SIGNED-FIELD

 Word => signed-word and {word, signed-word} => fixnum conversions
 are implemented with unchecked move VOPs.
Complete cut-to-width

 * Insert logand/mask-signed-field even around references to variables
   in modular arithmetic: avoid recursive rewriting by disabling the
   transform when the destination is a direct logand/mask-signed-field
   combination.

 * Fixes lp#1026634 (reported by Anton Marsden on sbcl-devel).