[ms-inline asm] Add a new Inline Asm Non-Standard Dialect attribute.

This new attribute is intended to be used by the backend to determine how
the inline asm string should be parsed/printed. This patch adds the 
ia_nsdialect attribute and also adds a test case to ensure the IR is
correctly parsed, but there is no functional change at this time.

The standard dialect is assumed to be AT&T.  Therefore, this attribute
should only be added to MS-style inline assembly statements, which use
the Intel dialect.  If we ever support more dialects we'll need to
add additional state to the attribute.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161641 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AsmParser/LLToken.h b/lib/AsmParser/LLToken.h
index 0461e7b..0b0b980 100644
--- a/lib/AsmParser/LLToken.h
+++ b/lib/AsmParser/LLToken.h
@@ -105,6 +105,7 @@
     kw_naked,
     kw_nonlazybind,
     kw_address_safety,
+    kw_ia_nsdialect,
 
     kw_type,
     kw_opaque,