[Fixed Point Arithmetic] Fixed Point to Boolean Cast

This patch is a part of https://reviews.llvm.org/D48456 in an attempt to split
the casting logic up into smaller patches. This contains the code for casting
from fixed point types to boolean types.

Differential Revision: https://reviews.llvm.org/D53308

llvm-svn: 345063
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 0f264af..e1e5c45 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1661,6 +1661,7 @@
   case CK_LValueBitCast:            // -> bool&
   case CK_UserDefinedConversion:    // operator bool()
   case CK_BuiltinFnToFnPtr:
+  case CK_FixedPointToBoolean:
   CheckNoBasePath:
     assert(path_empty() && "Cast kind should not have a base path!");
     break;