Replace APFloatBase static fltSemantics data members with getter functions

At least the plugin used by the LibreOffice build
(<https://wiki.documentfoundation.org/Development/Clang_plugins>) indirectly
uses those members (through inline functions in LLVM/Clang include files in turn
using them), but they are not exported by utils/extract_symbols.py on Windows,
and accessing data across DLL/EXE boundaries on Windows is generally
problematic.

Differential Revision: https://reviews.llvm.org/D26671

llvm-svn: 289647
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index 7f1d5d2..00bb476 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -983,7 +983,7 @@
 
   bool APFLosesInfo;
   APFloat APF = cFP->getValueAPF();
-  APF.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven, &APFLosesInfo);
+  APF.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven, &APFLosesInfo);
   *LosesInfo = APFLosesInfo;
   return APF.convertToDouble();
 }