Fix Subzero binary instruction to allow optional flags argument.

tests_lit/reader_tests/binop-forms.test

+; Test if we recognize both the old and the new forms of a binary instruction.
+
+; REQUIRES: no_minimal_build
+
+; Checks that new form of binary add (without flags argument) works.

[Jim Stichnoth, 2016/03/24 20:53:58]

"that the new" ?
(similar below)

[Karl, 2016/03/24 22:54:41]

Done.

+; RUN: %pnacl_sz -verbose inst,global_init -notranslate \
+; RUN:   -threads=0 -bitcode-as-text %p/Inputs/binop-newform.tbc \
+; RUN: | FileCheck %s
+
+; Checks that old form of binary add (with flags argument) works.
+; RUN: %pnacl_sz -verbose inst,global_init -notranslate \
+; RUN:   -threads=0 -bitcode-as-text %p/Inputs/binop-oldform.tbc \
+; RUN: | FileCheck %s
+
+; CHECK: define internal i32 @Function(i32 %__0, i32 %__1) { # Function(i=2:b=1)

[Jim Stichnoth, 2016/03/24 20:53:59]

Remove everything from "#" to the end of the line.

I don't promise that that output format is stable (which is why I put it at the
end of the line).

[Karl, 2016/03/24 22:54:41]

Done.

+; CHECK: __0:
+; CHECK:   %__2 = add i32 %__0, %__1
+; CHECK:   ret i32 %__2
+; CHECK: }