Coding Standards: Rename $c to $blog_count in wp-admin/admin.php.

Per the [https://developer.wordpress.org/coding-standards/wordpress-coding-standards/php/#naming-conventions Naming Conventions]:
> Don’t abbreviate variable names unnecessarily; let the code be unambiguous and self-documenting.

Follow-up to [https://mu.trac.wordpress.org/changeset/1940 mu:1940], [12712].

Props costdev, mukesh27.
See #63168.

git-svn-id: https://develop.svn.wordpress.org/trunk@60923 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-admin/admin.php

@@ -72,26 +72,30 @@
 	 * @param bool $do_mu_upgrade Whether to perform the Multisite upgrade routine. Default true.
 	 */
 	if ( apply_filters( 'do_mu_upgrade', true ) ) {
-		$c = get_blog_count();
+		$blog_count = get_blog_count();
 
 		/*
 		 * If there are 50 or fewer sites, run every time. Otherwise, throttle to reduce load:
 		 * attempt to do no more than threshold value, with some +/- allowed.
 		 */
-		if ( $c <= 50 || ( $c > 50 && mt_rand( 0, (int) ( $c / 50 ) ) === 1 ) ) {
+		if ( $blog_count <= 50 || ( $blog_count > 50 && mt_rand( 0, (int) ( $blog_count / 50 ) ) === 1 ) ) {
 			require_once ABSPATH . WPINC . '/http.php';
+
 			$response = wp_remote_get(
 				admin_url( 'upgrade.php?step=1' ),
 				array(
 					'timeout'     => 120,
 					'httpversion' => '1.1',
 				)
 			);
+
 			/** This action is documented in wp-admin/network/upgrade.php */
 			do_action( 'after_mu_upgrade', $response );
+
 			unset( $response );
 		}
-		unset( $c );
+
+		unset( $blog_count );
 	}
 }