Target: invert condition for Windows

The Microsoft ABI and MSVCRT are considered the canonical C runtime and ABI.
The long double routines are not part of this environment.  However, cygwin and
MinGW both provide supplementary implementations.  Change the condition to
reflect this reality.

llvm-svn: 213896

llvm/lib/Target/TargetLibraryInfo.cpp

@@ -426,7 +426,7 @@ static void initialize(TargetLibraryInfo &TLI, const Triple &T,
     TLI.setUnavailable(LibFunc::fiprintf);
   }
 
-  if (T.isKnownWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
+  if (T.isOSWindows() && !T.isOSCygMing()) {
     // Win32 does not support long double
     TLI.setUnavailable(LibFunc::acosl);
     TLI.setUnavailable(LibFunc::asinl);