Added some 2-line source files to get a direct correspondence

between sources and objects.  This will be used to avoid messy
special cases in Makefile.inc.

lib/libc/string/bzero.c

@@ -0,0 +1,2 @@
+#define	BZERO
+#include "memset.c"

lib/libc/string/memcpy.c

@@ -0,0 +1,2 @@
+#define	MEMCOPY
+#include "bcopy.c"

lib/libc/string/memmove.c

@@ -0,0 +1,2 @@
+#define	MEMMOVE
+#include "bcopy.c"

lib/libc/string/strchr.c

@@ -0,0 +1,2 @@
+#define	STRCHR
+#include "index.c"

lib/libc/string/strrchr.c

@@ -0,0 +1,2 @@
+#define	STRRCHR
+#include "rindex.c"