Just return true from wxString::Shrink()

The comparison of lengths() seems to be completely unnecessary.

Also document that Shrink() always returns true.

interface/wx/string.h

@@ -1428,8 +1428,12 @@ public:
     bool Alloc(size_t nLen);
 
     /**
-        Minimizes the string's memory. This can be useful after a call to
+        Minimizes the string's memory.
-        Alloc() if too much memory were preallocated.
+
+        This can be useful after a call to Alloc() if too much memory were
+        preallocated.
+
+        @return Always returns @true
     */
     bool Shrink();
 

src/common/string.cpp

@@ -555,7 +555,7 @@ bool wxString::Shrink()
 {
   wxString tmp(begin(), end());
   swap(tmp);
-  return tmp.length() == length();
+  return true;
 }
 
 // deprecated compatibility code: