Fix typos identified using codespell

See https://github.com/codespell-project/codespell#readme

The following command was used:

```
codespell -q6 --skip="\
.git,\
*.json,\
./Copyright.txt,\
./Help/command/foreach.rst,\
./Help/prop_test/REQUIRED_FILES.rst,\
./Help/variable/CTEST_COVERAGE_COMMAND.rst,\
./Modules/CMakeCheckCompilerFlagCommonPatterns.cmake,\
./Modules/CMakeRCInformation.cmake,\
./Modules/Internal/CPack/NSIS.template.in,\
./Modules/FindMatlab.cmake,\
./Modules/MatlabTestsRedirect.cmake,\
./Modules/Platform/Windows-Clang.cmake,\
./Modules/Platform/Windows-Intel-Fortran.cmake,\
./Modules/Platform/Windows-MSVC.cmake,\
./Source/CMakeVersion.cmake,\
./Source/cmConvertMSBuildXMLToJSON.py,\
./Source/cmCreateTestSourceList.cxx,\
./Source/cmGlobalVisualStudio10Generator.cxx,\
./Source/cmExportBuildFileGenerator.cxx,\
./Source/cmExportInstallAndroidMKGenerator.cxx,\
./Source/cmExportInstallFileGenerator.cxx,\
./Source/cmExportSet.cxx,\
./Source/cmExportTryCompileFileGenerator.cxx,\
./Source/cmFindPackageCommand.cxx,\
./Source/cmInstallCommand.cxx,\
./Source/cmGeneratorExpressionLexer.cxx,\
./Source/cmLocalVisualStudio7Generator.cxx,\
./Source/cmOrderDirectories.cxx,\
./Source/cmTarget.cxx,\
./Source/kwsys/*,\
./Source/QtDialog/CMakeSetupDialog.ui,\
./Source/CPack/WiX/cmWIXRichTextFormatWriter.cxx,\
./Source/CTest/cmParseCoberturaCoverage.h,\
./Tests/CMakeTests/ImplicitLinkInfoTest.cmake.in,\
./Tests/RunCMake/CPack/tests/DMG_SLA/English.license.rtf,\
./Tests/RunCMake/CPack/tests/DMG_SLA/German.license.txt,\
./Tests/RunCMake/CPack/tests/DMG_SLA/German.menu.txt,\
./Tests/RunCMake/GoogleTest/xml_output.cpp,\
./Tests/RunCMake/Make/TargetMessages*,\
./Utilities/*,\
" \
-L "\
dependees,\
endwhile,\
fo,\
filetest,\
helpfull,\
nd,\
objext,\
stoll,\
supercedes,\
superceded,\
vas,\
varn,\
"
```

1 files changed, 2 insertions, 2 deletions

diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 4fe68d2..b10ce89 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -3164,7 +3164,7 @@ void cmGeneratorTarget::AddCUDAArchitectureFlags(std::string& flags) const
         } else {
           this->Makefile->IssueMessage(
             MessageType::FATAL_ERROR,
-            "Uknown CUDA architecture specifier \"" + std::string(specifier) +
+            "Unknown CUDA architecture specifier \"" + std::string(specifier) +
               "\".");
         }
       }
@@ -3880,7 +3880,7 @@ std::string cmGeneratorTarget::GetPchSource(const std::string& config,
       cmStrCat(generatorTarget->LocalGenerator->GetCurrentBinaryDirectory(),
                "/CMakeFiles/", generatorTarget->GetName(), ".dir/cmake_pch");
 
-    // For GCC the source extension will be tranformed into .h[xx].gch
+    // For GCC the source extension will be transformed into .h[xx].gch
     if (!this->Makefile->IsOn("CMAKE_LINK_PCH")) {
       const std::map<std::string, std::string> languageToExtension = {
         { "C", ".h.c" },