asm-llvm: implement MemberExpression, CallExpression, and AssignmentExpression.

Only missing one case now:
  x:Identifier[index:Expression & n:NumericLiteral](arg:Expression,...)

I also need to better handle the two forward-reference cases: referencing
a local function before it's defined, and referencing a function table.

Fixed some test cases that didn't validate once we started checking
assignments.
Print filenames in bin/compile-asm-llvm.js.

This helps make it clear who's responsible for the syntax error when
I'm running test cases against asm-llvm.