Fix minor clang-tidy findings

Fix issues diagnosed by clang-tidy
 - modernize-use-bool-literals
 - misc-string-integer-assignment
 - performance-faster-string-find
 - readability-redundant-string-cstr
 - readability-delete-null-pointer

Signed-off-by: Matthias Maennich <matthias@maennich.net>

Source/CPack/cmCPackProductBuildGenerator.cxx

@@ -190,7 +190,7 @@ bool cmCPackProductBuildGenerator::GenerateComponentPackage(
     cmCPackLogger(cmCPackLog::LOG_ERROR,
                   "Problem creating installer directory: " << scriptDir
                                                            << std::endl);
-    return 0;
+    return false;
   }
 
   // if preflight, postflight, or postupgrade are set

Source/cmFindLibraryCommand.cxx

@@ -260,7 +260,7 @@ void cmFindLibraryHelper::RegexFromLiteral(std::string& out,
       out += "\\";
     }
 #if defined(_WIN32) || defined(__APPLE__)
-    out += tolower(ch);
+    out += static_cast<char>(tolower(ch));
 #else
     out += ch;
 #endif

Source/cmGlobalXCodeGenerator.cxx

@@ -1471,7 +1471,7 @@ void cmGlobalXCodeGenerator::FilterConfigurationAttribute(
     return;
   }
 
-  std::string::size_type endVariant = attribute.find("]", beginVariant + 9);
+  std::string::size_type endVariant = attribute.find(']', beginVariant + 9);
   if (endVariant == std::string::npos) {
     // There is no terminating bracket.
     return;
@@ -2894,7 +2894,7 @@ bool cmGlobalXCodeGenerator::CreateXCodeObjects(
   std::string project_id = "PROJECT_";
   project_id += root->GetProjectName();
   this->RootObject->SetId(
-    this->GetOrCreateId(project_id.c_str(), this->RootObject->GetId()));
+    this->GetOrCreateId(project_id, this->RootObject->GetId()));
 
   group = this->CreateObject(cmXCodeObject::ATTRIBUTE_GROUP);
   this->RootObject->AddAttribute("mainGroup",

Source/cmInstalledFile.cxx

@@ -16,9 +16,7 @@ cmInstalledFile::cmInstalledFile()
 
 cmInstalledFile::~cmInstalledFile()
 {
-  if (NameExpression) {
-    delete NameExpression;
-  }
+  delete NameExpression;
 }
 
 cmInstalledFile::Property::Property()