tools: wc, head, and an argc/argv demo (args) + libc.c helpers

- c/libc.c: shared C helpers linked into every program - putu (print decimal),
  atou (parse decimal), argv_parse (tokenize getargs() into argc/argv).
- wc: count lines/words/chars of stdin. head [n]: first n lines (drains rest to
  EOF). args: argc/argv demo.
- pid now uses libc putu; build.sh links libc.c; Makefile CBLOBS + libc dep.
- README: document the new tools + argv_parse.
- verified: 'args one two three' -> argc=3/argv[..]; wc '2 3 16'; head 2.

1 files changed, 5 insertions, 0 deletions

diff --git a/c/gbos.h b/c/gbos.h
index 3a10e06..cf94128 100644
--- a/c/gbos.h
+++ b/c/gbos.h
@@ -12,4 +12,9 @@ char         *getargs(void);              /* this program's argument string */
 char          readc(void);                /* one input byte, EOF at end    */
 void          sexit(unsigned char code);
 unsigned char getpid(void);
+
+/* helpers (c/libc.c) */
+void          putu(unsigned int n);              /* print decimal          */
+unsigned char atou(const char *s);               /* parse decimal          */
+unsigned char argv_parse(char **argv, unsigned char maxv); /* argc/argv     */
 #endif