Remove whitespace inside <methodname> tags

Remove leading/trailing whitespace around <replaceable> inside
<methodname> tags in setprogressmonitor.xml and
user-level-output-buffers.xml. These were the only two occurrences
in the entire manual and caused issues with PhD link resolution
and translation QA tools.

See php/phd#237

Author: lacatoire

reference/imagick/imagick/setprogressmonitor.xml

@@ -33,9 +33,7 @@
 
      <methodsynopsis xmlns="http://docbook.org/ns/docbook">
       <type>bool</type>
-      <methodname>
-       <replaceable>callback</replaceable>
-      </methodname>
+      <methodname><replaceable>callback</replaceable></methodname>
       <methodparam>
        <type>mixed</type><parameter>offset</parameter>
       </methodparam>

reference/outcontrol/user-level-output-buffers.xml

@@ -342,9 +342,7 @@
   <para>
    <methodsynopsis>
     <type>string</type>
-    <methodname>
-     <replaceable>handler</replaceable>
-    </methodname>
+    <methodname><replaceable>handler</replaceable></methodname>
     <methodparam>
      <type>string</type>
      <parameter>buffer</parameter>