BadFunctions/EasyRFI: use the build-in PHPCS functionality [1]

The PHPCS [`addError()`](https://pear.php.net/package/PHP_CodeSniffer/docs/3.5.4/apidoc/PHP_CodeSniffer/File.html#methodaddError) and [`addWarning()`](https://pear.php.net/package/PHP_CodeSniffer/docs/3.5.4/apidoc/PHP_CodeSniffer/File.html#methodaddWarning) functions have a build-in string replacement `sprintf()`-like functionality, so let's use it.

Author: jrfnl

Security/Sniffs/BadFunctions/EasyRFISniff.php

@@ -50,12 +50,18 @@ public function process(File $phpcsFile, $stackPtr) {
 		}
 		while ($s) {
 			$s = $phpcsFile->findNext($this->search, $s + 1, $closer, true);
+
+			$data = array(
+				$tokens[$s]['content'],
+				$tokens[$stackPtr]['content'],
+			);
+
 			if ($s && $utils::is_token_user_input($tokens[$s])) {
 				if (\PHP_CodeSniffer\Config::getConfigData('ParanoiaMode') || !$utils::is_token_false_positive($tokens[$s], $tokens[$s+2])) {
-					$phpcsFile->addError('Easy RFI detected because of direct user input with ' . $tokens[$s]['content'] . ' on ' . $tokens[$stackPtr]['content'], $s, 'ErrEasyRFI');
+					$phpcsFile->addError('Easy RFI detected because of direct user input with %s on %s', $s, 'ErrEasyRFI', $data);
 				}
 			} elseif ($s && \PHP_CodeSniffer\Config::getConfigData('ParanoiaMode') && $tokens[$s]['content'] != '.') {
-				$phpcsFile->addWarning('Possible RFI detected with ' . $tokens[$s]['content'] . ' on ' . $tokens[$stackPtr]['content'], $s, 'WarnEasyRFI');
+				$phpcsFile->addWarning('Possible RFI detected with %s on %s', $s, 'WarnEasyRFI', $data);
 			}
 		}
 	}