libc: Cleanup FreeBSD files

Remove code specific to FreeBSD so that they can be used in this
repository.

Change-Id: I5c11eb5b3c05a7fb91aed08371a1f7a0e6122a94
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/lib/libc/strchr.c b/lib/libc/strchr.c
index 61244da..d94bb9e 100644
--- a/lib/libc/strchr.c
+++ b/lib/libc/strchr.c
@@ -29,11 +29,10 @@
  * SUCH DAMAGE.
  */
 
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)index.c	8.1 (Berkeley) 6/4/93";
-#endif /* LIBC_SCCS and not lint */
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
+/*
+ * Portions copyright (c) 2018, ARM Limited and Contributors.
+ * All rights reserved.
+ */
 
 #include <stddef.h>
 #include <string.h>
@@ -52,5 +51,3 @@
 	}
 	/* NOTREACHED */
 }
-
-__weak_reference(strchr, index);