Reintroduce the InlineHint function attribute.

This time it's for real! I am going to hook this up in the frontends as well.

The inliner has some experimental heuristics for dealing with the inline hint.
When given a -respect-inlinehint option, functions marked with the inline
keyword are given a threshold just above the default for -O3.

We need some experiments to determine if that is the right thing to do.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95466 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AsmParser/LLToken.h b/lib/AsmParser/LLToken.h
index 80eb194..7f1807c 100644
--- a/lib/AsmParser/LLToken.h
+++ b/lib/AsmParser/LLToken.h
@@ -85,6 +85,7 @@
     kw_readnone,
     kw_readonly,
 
+    kw_inlinehint,
     kw_noinline,
     kw_alwaysinline,
     kw_optsize,