libsysprof-capture: Use strlcpy() instead of g_strlcpy()

If the system doesn’t provide `strlcpy()` (FreeBSD does, Linux doesn’t),
use an inbuilt copy instead.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Helps: #40

src/libsysprof-capture/sysprof-capture-util-private.h

@@ -89,5 +89,12 @@ ssize_t _sysprof_sendfile    (int         out_fd,
                               int         in_fd,
                               off_t      *offset,
                               size_t      count);
-
+#endif
+
+#ifdef HAVE_STRLCPY
+# define _sysprof_strlcpy(d,s,ds) strlcpy(d,s,ds)
+#else
+size_t  _sysprof_strlcpy     (char       *dest,
+                              const char *src,
+                              size_t      dest_size);
 #endif