Add in-class initialization of some members

Several class constructors leave members uninitialized.  The members are
initialized before use in methods, but it is clearer and less
error-prone to initialize them at their definition site.

Source/cmConfigureFileCommand.h

@@ -32,9 +32,9 @@ private:
 
   std::string InputFile;
   std::string OutputFile;
-  bool CopyOnly;
-  bool EscapeQuotes;
-  bool AtOnly;
+  bool CopyOnly = false;
+  bool EscapeQuotes = false;
+  bool AtOnly = false;
 };
 
 #endif

Source/cmCoreTryCompile.h

@@ -46,7 +46,7 @@ protected:
   std::string BinaryDirectory;
   std::string OutputFile;
   std::string FindErrorMessage;
-  bool SrcFileSignature;
+  bool SrcFileSignature = false;
 
 private:
   std::vector<std::string> WarnCMP0067;

Source/cmExportLibraryDependenciesCommand.h

@@ -27,7 +27,7 @@ public:
 
 private:
   std::string Filename;
-  bool Append;
+  bool Append = false;
   void ConstFinalPass() const;
 };
 

Source/cmExternalMakefileProjectGenerator.h

@@ -62,7 +62,7 @@ protected:
   ///! Contains the names of the global generators support by this generator.
   std::vector<std::string> SupportedGlobalGenerators;
   ///! the global generator which creates the makefiles
-  const cmGlobalGenerator* GlobalGenerator;
+  const cmGlobalGenerator* GlobalGenerator = nullptr;
 
   std::string Name;
 };

Source/cmInstallFilesCommand.h

@@ -48,7 +48,7 @@ protected:
 
 private:
   std::vector<std::string> FinalArgs;
-  bool IsFilesForm;
+  bool IsFilesForm = false;
   std::string Destination;
   std::vector<std::string> Files;
 };

Source/cmTargetLinkLibrariesCommand.h

@@ -43,7 +43,7 @@ private:
   void LinkLibraryTypeSpecifierWarning(int left, int right);
   static const char* LinkLibraryTypeNames[3];
 
-  cmTarget* Target;
+  cmTarget* Target = nullptr;
   enum ProcessingState
   {
     ProcessingLinkLibraries,
@@ -55,7 +55,7 @@ private:
     ProcessingKeywordPrivateInterface
   };
 
-  ProcessingState CurrentProcessingState;
+  ProcessingState CurrentProcessingState = ProcessingLinkLibraries;
 
   bool HandleLibrary(const std::string& lib, cmTargetLinkLibraryType llt);
 };

Source/cmTargetPropCommandBase.h

@@ -28,7 +28,7 @@ public:
 
 protected:
   std::string Property;
-  cmTarget* Target;
+  cmTarget* Target = nullptr;
 
   virtual void HandleInterfaceContent(cmTarget* tgt,
                                       const std::vector<std::string>& content,