find-unneeded-includes: warn about fw decls in namespaces too

This regex parsed unneeded fw declarations reported by IWYU in the form of:
class foo;
But not ones inside namespaces, e.g.:
namespace foo { class bar; }
namespace com { namespace sun { namespace star { namespace foo { class bar; } } } }

Change-Id: Ie2962b9fb1cf9382e8da45903f3716d0311dd58e
Reviewed-on: https://gerrit.libreoffice.org/61485
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

bin/find-unneeded-includes

@@ -155,7 +155,7 @@ def processIWYUOutput(iwyuOutput, moduleRules):
                     toRemove.append("%s:%s: %s" % (currentFileName, lineno, include))
                 continue
 
-            match = re.match("- (.*);  // lines (.*)-.*", line)
+            match = re.match("- (.*;(?: })*)*  // lines (.*)-.*", line)
             if match:
                 fwdDecl = match.group(1)
                 lineno = match.group(2)