[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