Add strchr() and putchar() to local C library

Change-Id: I3659e119a242f8ef828e32bfdf5d0b4b7ac4f716
diff --git a/include/stdlib/stdio.h b/include/stdlib/stdio.h
index 517158a..f59a115 100644
--- a/include/stdlib/stdio.h
+++ b/include/stdlib/stdio.h
@@ -59,6 +59,7 @@
 #define	EOF	(-1)
 
 int	 printf(const char * __restrict, ...);
+int	 putchar(int);
 int	 puts(const char *);
 int	 sprintf(char * __restrict, const char * __restrict, ...);
 int	 vsprintf(char * __restrict, const char * __restrict,