include strings.h where appriopriate...

instead or additionally to string.h, in preparation for functions move.
* moves str[n]casecmp() functions and others to strings.h.
* strings.h doesn't include string.h anymore.
* this solves #10949

headers/posix/strings.h

@@ -1,6 +1,34 @@
+/*
+ * Copyright 2014 Haiku, Inc. All Rights Reserved.
+ * Distributed under the terms of the MIT License.
+ */
 #ifndef _STRINGS_H_
 #define _STRINGS_H_
 
-#include <string.h>
+
+#include <sys/types.h>
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int ffs(int i);
+
+extern int		strcasecmp(const char *string1, const char *string2);
+extern int		strncasecmp(const char *string1, const char *string2,
+	size_t length);
+
+/* legacy compatibility -- might be removed one day */
+#define bcmp(a, b, length) memcmp((a), (b), (length))
+#define bcopy(source, dest, length) memmove((dest), (source), (length))
+#define bzero(buffer, length) memset((buffer), 0, (length))
+
+extern char 		*index(const char *s, int c);
+extern char 		*rindex(char const *s, int c);
+
+#ifdef __cplusplus
+}
+#endif
 
 #endif	/* _STRINGS_H_ */