CMake: don't use else after return

Source/cmArchiveWrite.cxx

Source/cmCTest.cxx

Source/cmCacheManager.cxx

Source/cmCommandArgumentParserHelper.cxx

Source/cmCryptoHash.cxx

Source/cmDependsFortran.cxx

Source/cmDocumentation.cxx

Source/cmELF.cxx

Source/cmExportBuildFileGenerator.cxx

Source/cmExprParserHelper.cxx

Source/cmExtraCodeBlocksGenerator.cxx

Source/cmFileLockPool.cxx

Source/cmFileTimeComparison.cxx

Source/cmFortranParserImpl.cxx

Source/cmGeneratorExpression.cxx

Source/cmGeneratorExpressionEvaluator.cxx

Source/cmGeneratorExpressionNode.cxx

Source/cmGeneratorTarget.cxx

Source/cmGlobalNinjaGenerator.cxx

Source/cmInstallExportGenerator.cxx