rename lib/errors.* to lib/lib_errors.* due to conflict with ps/errors.*

also add sys_error_description_r backend for unix

This was SVN commit r3160.

source/lib/lib.h

@@ -61,7 +61,7 @@ scope
 
 // define error codes
 #define ERR(err, id, str) const int id = err;
-#include "lib/errors.h"
+#include "lib/lib_errors.h"
 
 #include "sysdep/sysdep.h"
 #include "sysdep/cpu.h"	// CAS

source/lib/lib_errors.cpp

@@ -1,6 +1,10 @@
+// note: this is called lib_errors.cpp because we have another
+// errors.cpp; the MS linker isn't smart enough to deal with
+// object files of the same name but in different paths.
+
 #include "precompiled.h"
 
-#include "errors.h"
+#include "lib_errors.h"
 #include "sysdep/sysdep.h"
 
 #include <string.h>
@@ -16,7 +20,7 @@ static const char* lib_error_description(int err)
 	switch(err)
 	{
 #define ERR(err, id, str) case id: return str;
-#include "errors.h"
+#include "lib_errors.h"
 	default: return "Unknown lib error";
 	}
 	UNREACHABLE;

source/lib/lib_errors.h

@@ -1,3 +1,7 @@
+// note: this is called lib_errors.h because we have another
+// errors.cpp; the MS linker isn't smart enough to deal with
+// object files of the same name but in different paths.
+
 // X macros: error code, symbolic name in code, user-visible string.
 // error code is usually negative; positive denotes warnings.
 //   its absolute value must be within [ERR_MIN, ERR_MAX).

source/lib/sysdep/unix/unix.cpp

@@ -121,3 +121,11 @@ int sys_cursor_free(void* cursor)
 {
 	return 0;
 }
+
+int sys_error_description_r(int err, char* buf, size_t max_chars)
+{
+	// don't need to do anything: lib/errors.cpp already queries
+	// libc's strerror(). if we ever end up needing translation of
+	// e.g. Qt or X errors, that'd go here.
+	return -1;
+}