Move unicode Python script into libstd_unicode crate.

The only place this Python script is used is inside the libstd_unicode
crate, so lets move it there.

Author: frewsxcv

src/libstd_unicode/tables.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// NOTE: The following code was generated by "src/etc/unicode.py", do not edit directly
+// NOTE: The following code was generated by "./unicode.py", do not edit directly
 
 #![allow(missing_docs, non_upper_case_globals, non_snake_case)]
 

src/etc/unicode.py renamed to src/libstd_unicode/unicode.py

@@ -35,7 +35,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// NOTE: The following code was generated by "src/etc/unicode.py", do not edit directly
+// NOTE: The following code was generated by "./unicode.py", do not edit directly
 
 #![allow(missing_docs, non_upper_case_globals, non_snake_case)]
 '''