Remove local strnstr() implementation to fix compile error:
newlib/libc/iconv/lib/aliasesi.c:53:8: error: conflicting types for 'strnstr'
_DEFUN(strnstr, (haystack, needle, length),
^
In file included from newlib/libc/iconv/lib/aliasesi.c:29:0:
newlib/libc/include/string.h:125:10:
note: previous declaration of 'strnstr' was here
char *strnstr(const char *, const char *, size_t) __pure;
^~~~~~~
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>