In errno_md, for Sun and HP, always use strerror because it is always available and always thread safe on those systems. Linux, provide macro since there is no way to tell if available at runtime.

[SVN r36447]

libs/system

@@ -1 +1 @@
-Subproject commit 5688d4a3a24f52d0ba7e21a239379e38d890a88e
+Subproject commit 2fbf2718c4f6d4c79982f1b332fd67ec39a5bf42