Fix building with gcc 4.5

http://bugs.gentoo.org/show_bug.cgi?id=320377

--- src/mlview-ustring.cc
+++ src/mlview-ustring.cc
@@ -59,7 +59,7 @@
 UString::~UString ()
 {}
 
-UString::UString&
+UString&
 UString::operator= (const char *a_cstr)
 {
 	if (!a_cstr)