Remove unnecessary and somewhat inaccurate "C89" flag from language standards.

llvm-svn: 301500
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index dbbe6af..481ce5b 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1615,7 +1615,7 @@
   Opts.CPlusPlus1z = Std.isCPlusPlus1z();
   Opts.Digraphs = Std.hasDigraphs();
   Opts.GNUMode = Std.isGNUMode();
-  Opts.GNUInline = Std.isC89();
+  Opts.GNUInline = !Opts.C99 && !Opts.CPlusPlus;
   Opts.HexFloats = Std.hasHexFloats();
   Opts.ImplicitInt = Std.hasImplicitInt();