5a/a.h:
. Removed <u.h> and <lib.h>.
. Made definition of EOF conditional.

5a/a.y:
. Added <u.h> and <lib.h>.

5a/lex.c:
. Added <u.h> and <lib.h>.
. Dropped <ctype.h> (now in <u.h>).

5c/peep.c:
. Removed unnecessary "return 0" statement.

5c/reg.c:
. Added compilation condition around unused code.

5c/swt.c:
. Removed unused "thestring" argument from Bprint() calls.

5l/asm.c:
. Added USED() statements as required.
. Adjusted a few format specifications.
. Added compilation condition around unused code.

5l/l.h:
. Dropped directory prefix from <../5l/5.out.h>.
. Added varargck pragma for "I" and "i".

5l/obj.c:
. Cascaded consecutive "if" statements.
. Dropped unnecessary incrementation and assignments.

5l/pass.c:
. Dropped unnecessary assignment.

5l/prof.c:
. #if 0 converted to #ifdef NOTDEF.

5l/span.c:
. Dropped unnecessary incrementation and assignments.

R=golang-dev
CC=golang-dev, rsc
https://golang.org/cl/4752041