Switch to Generic.VersionControl.GitMergeConflict

Removes WordPressVIPMinimum.VersionControl.MergeConflict sniff.

The merge conflict boundary detection sniff in the built-in Generic standard is a more comprehensive sniff, and it means one less thing for VIP to maintain.

Requires PHPCS 3.4+ (made a requirement in #484).

Fixes #330.

WordPress-VIP-Go/ruleset-test.inc

@@ -567,12 +567,8 @@ $_SERVER['HTTP_X_FORWARDED_FOR']; // Error.
 $_SERVER["REMOTE_ADDR"]; // Error.
 // phpcs:enable WordPress.Security.ValidatedSanitizedInput.InputNotValidated,WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
 
-// WordPressVIPMinimum.VersionControl.MergeConflict
-function is_prime( $n ) {
-	if ( 2 === $n  ) {
-	}
-//phpcs:ignore Generic.PHP.Syntax.PHPSyntax
-======= // Error.
-	if ( $n % 2 === 0 ) {
-	}
-}
+// Generic.VersionControl.GitMergeConflict
+?>
+<<<<<<< HEAD // Error.
+
+>>>>>>> // Error.

WordPress-VIP-Go/ruleset-test.php

@@ -115,7 +115,8 @@
 		565 => 1,
 		566 => 1,
 		567 => 1,
-		575 => 1,
+		572 => 1,
+		574 => 1,
 	],
 	'warnings' => [
 		4   => 1,

WordPressVIPMinimum/ruleset-test.inc

@@ -604,15 +604,12 @@ function foo() {
 	$c = compact( $a, $b ); // Warning x 2.
 }
 
-// WordPressVIPMinimum.VersionControl.MergeConflict
-function is_prime( $n ) {
-	if ( 2 === $n  ) {
-	}
-//phpcs:ignore Generic.PHP.Syntax.PHPSyntax
-======= // Error.
-	if ( $n % 2 === 0 ) {
-	}
-}
+// Generic.VersionControl.GitMergeConflict
+?>
+<<<<<<< HEAD // Error.
+
+>>>>>>> // Error.
+<?php
 
 // Squiz.WhiteSpace.SuperfluousWhitespace
 // Error. ?>

WordPressVIPMinimum/ruleset-test.php

@@ -206,8 +206,9 @@
 		595 => 1,
 		596 => 1,
 		597 => 1,
-		612 => 1,
-		618 => 1,
+		609 => 1,
+		611 => 1,
+		615 => 1,
 	],
 	'warnings' => [
 		32  => 1,

WordPressVIPMinimum/ruleset.xml

@@ -42,6 +42,7 @@
 		</properties>
 	</rule>
 
+	<rule ref="Generic.VersionControl.GitMergeConflict"/>
 	<rule ref="Generic.NamingConventions.ConstructorName"/>
 	<rule ref="Generic.PHP.DisallowShortOpenTag"/>
 	<!-- Covers rule: Omitting the closing PHP tag at the end of a file is preferred. -->