Merge branch 'errno-const-macros' into 'master'

Test errno constant macros, make ENOTSUP available in Rust

See merge request redox-os/relibc!556

include/bits/errno.h

@@ -5,8 +5,6 @@
 extern "C" {
 #endif
 
-#define ENOTSUP EOPNOTSUPP
-
 #define errno (*__errno_location())
 #define program_invocation_name (*__program_invocation_name())
 #define program_invocation_short_name (*__program_invocation_short_name())