Add support for multi-value proposal (#861)

Use the `--enable-multi-value` flag to enable.

A lot of code already "worked" with multi-value, and just needed to
remove the restrictions. Most of the other changes are modifying the
callback APIs to be more general, e.g. taking more than 1 result type.

* Types are now stored as the negative values; this works nicely with
  the encoding of inline function types (used for block signatures),
  which are always positive values.
* Remove `BlockSignature` and use `BlockDeclaration` instead, which
  is just a typedef to `FuncSignature`. This allows for explicit or
  implicit type specifications on the block signatures.
* Allow for >1 "keep" values in the DropKeep interpreter instruction

1 files changed, 3 insertions, 3 deletions

diff --git a/test/spec/if.txt b/test/spec/if.txt
index d7f9118a..db286d16 100644
--- a/test/spec/if.txt
+++ b/test/spec/if.txt
@@ -41,14 +41,14 @@ out/test/spec/if.wast:242: assert_invalid passed:
   error: type mismatch in if true branch, expected [i32] but got []
   000001d: error: OnElseExpr callback failed
 out/test/spec/if.wast:248: assert_invalid passed:
-  error: if without else cannot have type signature.
+  error: if without else cannot have results.
   000001f: error: OnEndExpr callback failed
 out/test/spec/if.wast:254: assert_invalid passed:
-  error: if without else cannot have type signature.
+  error: if without else cannot have results.
   error: type mismatch in if, expected [i32] but got []
   000001d: error: OnEndExpr callback failed
 out/test/spec/if.wast:260: assert_invalid passed:
-  error: if without else cannot have type signature.
+  error: if without else cannot have results.
   000001f: error: OnEndExpr callback failed
 out/test/spec/if.wast:267: assert_invalid passed:
   error: type mismatch in if true branch, expected [i32] but got []