Fix #8841 (broken localization support for 3rd-party apps).

* made private Catalog.h header public by moving it to 
  os/locale/tools/CollectingCatalog.h
* reintroduce B_COLLECTING_CATKEYS define (which is expected to be set
  during a collectcatkeys session) in order to decide whether or not
  to automatically include the CollecingCatalog.h header from Catalog.h
* adjust jam rule for collecting catalog keys accordingly

headers/os/locale/Catalog.h

@@ -86,6 +86,13 @@ private:
 	// Tip: Use a descriptive name of the class implemented in that
 	//		source-file.
 
+#ifdef B_COLLECTING_CATKEYS
+
+// pull in all the macros used when collecting catalog keys.
+#include <tools/CollectingCatalog.h>
+
+#else
+
 // Translation macros which may be used to shorten translation requests:
 #undef B_TRANSLATE
 #define B_TRANSLATE(string) \
@@ -172,7 +179,7 @@ private:
 #undef B_TRANSLATE_MARK_SYSTEM_NAME_VOID
 #define B_TRANSLATE_MARK_SYSTEM_NAME_VOID(string)
 
-// Translation macros which do not let collectcatkeys try to collect the key
+// Translation macros which cause collectcatkeys to ignore this key
 // (useful in combination with the marking macros above):
 #undef B_TRANSLATE_NOCOLLECT
 #define B_TRANSLATE_NOCOLLECT(string) \
@@ -194,6 +201,8 @@ private:
 #define B_TRANSLATE_NOCOLLECT_SYSTEM_NAME(string) \
 	B_TRANSLATE_SYSTEM_NAME(string)
 
+#endif	/* B_COLLECTING_CATKEYS */
+
 #endif	/* B_AVOID_TRANSLATION_MACROS */
 
 

headers/os/locale/tools/CollectingCatalog.h

@@ -2,16 +2,11 @@
  * Copyright 2012, Haiku, Inc.
  * Distributed under the terms of the MIT License.
  */
-#ifndef _COLLECTING_CATALOG_H_
-#define _COLLECTING_CATALOG_H_
-
-
-#include_next <Catalog.h>
+#ifndef _TOOLS_COLLECTING_CATALOG_H_
+#define _TOOLS_COLLECTING_CATALOG_H_
 
 
 // Translation macros used when executing collectcatkeys
-#undef B_TRANSLATION_CONTEXT
-
 #undef B_TRANSLATE
 #define B_TRANSLATE(string) \
 	B_CATKEY((string), B_TRANSLATION_CONTEXT)