Fix errno.h definition

include/errno.h

-extern int errno;
+extern __thread int errno;

src/lib.rs

@@ -9,6 +9,7 @@ extern crate errno;
 extern crate fcntl;
 extern crate grp;
 extern crate mman;
+extern crate semaphore;
 extern crate stdio;
 extern crate stdlib;
 extern crate string;

tests/.gitignore

@@ -6,6 +6,7 @@
 /create.out
 /dup
 /dup.out
+/error
 /fchdir
 /fsync
 /ftruncate

tests/Makefile

@@ -5,6 +5,7 @@ BINS=\
 	chdir \
 	create \
 	dup \
+	error \
 	fchdir \
 	fsync \
 	ftruncate \