Rewrite parser as recursive descent (#591)

* Remove Bison dependency
* Remove pre-generated parser files
* Rename build config from no-re2c-bison to no-re2c
* Add a simple make_unique implementation
* Move handling of module bindings into ir.cc
* Simplify lexer
  - Remove lookahead, the parser handles this now
  - Unify Token/LexerToken, it only contains terminal values now
  - Refactor setting token type and value into one function (e.g.
    LITERAL, RETURN => RETURN_LITERAL)
* New Parser
  - Uses two tokens of lookahead (use Peek(0) or Peek(1))
  - Consume() consumes one token of any kind
  - Match(t) consumes the current token if it matches
  - PeekMatch(t) returns true iff the token matches, but doesn't consume
  - Basic error synchronization; plenty of room for improvement here

1 files changed, 2 insertions, 8 deletions

diff --git a/test/spec/token.txt b/test/spec/token.txt
index bab6656e..4c114f55 100644
--- a/test/spec/token.txt
+++ b/test/spec/token.txt
@@ -2,18 +2,12 @@
 ;;; STDIN_FILE: third_party/testsuite/token.wast
 (;; STDOUT ;;;
 out/third_party/testsuite/token.wast:4: assert_malformed passed:
-  out/third_party/testsuite/token/token.0.wast:1:14: error: unexpected token "i32.const0"
+  out/third_party/testsuite/token/token.0.wast:1:14: error: unexpected token "i32.const0", expected an expr.
   (func (drop (i32.const0)))
                ^^^^^^^^^^
-  out/third_party/testsuite/token/token.0.wast:1:24: error: syntax error, unexpected )
-  (func (drop (i32.const0)))
-                         ^
 out/third_party/testsuite/token.wast:8: assert_malformed passed:
-  out/third_party/testsuite/token/token.1.wast:1:10: error: unexpected token "0drop"
+  out/third_party/testsuite/token/token.1.wast:1:10: error: unexpected token "0drop", expected a numeric index or a name (e.g. 12 or $foo).
   (func br 0drop)
            ^^^^^
-  out/third_party/testsuite/token/token.1.wast:1:15: error: syntax error, unexpected ), expecting NAT or VAR
-  (func br 0drop)
-                ^
 2/2 tests passed.
 ;;; STDOUT ;;)