Coding Standards: Fix instances of WordPress.PHP.NoSilencedErrors.Discouraged.

Noteable changes:
- The `magic_quotes_runtime` and `magic_quotes_sybase` settings were removed in PHP 5.4, so no longer need to be set.
- Some functions that use external libraries can generate errors that can't be tested for, so are globally allowed to silence errors.
- Quite a few functions would cause errors if `safe_mode` was set. This setting was removed in PHP 5.4.
- Only a handful of `header()` calls needed corresponding `headers_sent()` checks for unit tests to pass, but more may need to be added as the nightlies builds are tested.

See #46732.


git-svn-id: https://develop.svn.wordpress.org/trunk@45611 602fd350-edb4-49c9-b593-d223f7449a82

phpcs.xml.dist

@@ -221,6 +221,27 @@
 		</properties>
 	</rule>
 
+	<rule ref="WordPress.PHP.NoSilencedErrors">
+		<properties>
+			<property name="custom_whitelist" type="array">
+				<element value="ssh2_connect"/>
+				<element value="ssh2_auth_password"/>
+				<element value="ssh2_auth_pubkey_file"/>
+				<element value="ftp_ssl_connect"/>
+				<element value="ftp_connect"/>
+				<element value="ftp_get_option"/>
+				<element value="ftp_set_option"/>
+				<element value="disk_free_space"/>
+				<element value="getimagesize"/>
+				<element value="iptcparse"/>
+				<element value="exif_read_data"/>
+				<element value="gzinflate"/>
+				<element value="gzuncompress"/>
+				<element value="gzdecode"/>
+			</property>
+		</properties>
+	</rule>
+
 	<!-- Assignments in while conditions are a valid method of looping over iterables -->
 	<rule ref="WordPress.CodeAnalysis.AssignmentInCondition.FoundInWhileCondition">
 		<exclude-pattern>*</exclude-pattern>