Upgrade system and filesystem to conform system_category and generic_category interface to N3090, the current C++0x working paper, section 19.5, System error support.

Refactor API macros into a new header, boost/system/api_config.hpp.

Prohibit user definition of API macros. Rationale: ensure all translation units use same definitions, cut number of environments that need to be tested.

[SVN r62313]

libs/filesystem

@@ -1 +1 @@
-Subproject commit c855c033b604497a45dbac01e28da4aa7075f34c
+Subproject commit 91715967a54b5ccde9579b60af133e8f957999c4

libs/system

@@ -1 +1 @@
-Subproject commit 2565e5307b0d75d01abe4b7d6f2393f8f25a2778
+Subproject commit baae3a392aabe2790a65b76e1ad82ca495a0315c