add libc building to agbcc.

libc/string/bzero.c

@@ -0,0 +1,42 @@
+/*
+FUNCTION
+<<bzero>>---initialize memory to zero
+
+INDEX
+	bzero
+
+ANSI_SYNOPSIS
+	#include <string.h>
+	void bzero(char *<[b]>, size_t <[length]>);
+
+TRAD_SYNOPSIS
+	#include <string.h>
+	void bzero(<[b]>, <[length]>)
+	char *<[b]>;
+	size_t <[length]>;
+
+DESCRIPTION
+<<bzero>> initializes <[length]> bytes of memory, starting at address
+<[b]>, to zero.
+
+RETURNS
+<<bzero>> does not return a result.
+
+PORTABILITY
+<<bzero>> is in the Berkeley Software Distribution.
+Neither ANSI C nor the System V Interface Definition (Issue 2) require
+<<bzero>>.
+
+<<bzero>> requires no supporting OS subroutines.
+*/
+
+#include <string.h>
+
+_VOID
+_DEFUN (bzero, (b, length),
+	char *b _AND
+	size_t length)
+{
+  while (length--)
+    *b++ = 0;
+}