isDefinition() should return IsDefinition.

Swift SVN r10825

Author: Manman Ren

include/swift/SIL/SILGlobalVariable.h

@@ -74,7 +74,7 @@ class SILGlobalVariable
   /// True if this is a declaration of a variable defined in another module.
   bool isExternalDeclaration() const { return !IsDefinition; }
   /// True if this is a definition of the variable.
-  bool isDefinition() const { return !IsDefinition; }
+  bool isDefinition() const { return IsDefinition; }
   void setDefinition(bool b) { IsDefinition = b; }
 
   /// Get this function's linkage attribute.