Fix some overlap mismatch

This was caught by the following test:

```

int main(void) {
    char c[32];
    memcpy(c, c + 16, 16);
}
```

Reported-by: q66

1 files changed, 2 insertions, 2 deletions

diff --git a/include/fortify-headers.h b/include/fortify-headers.h
index ea2e430..796fd2d 100644
--- a/include/fortify-headers.h
+++ b/include/fortify-headers.h
@@ -141,8 +141,8 @@
  * since gcc seems to like to generate code that relies on dst == src */
 #define __fh_overlap(a, len_a, b, len_b) \
         ( \
-                ((a) < (b) && (b) < (a) + (__fh_size_t)(len_a)) \
-             || ((b) < (a) && (a) < (b) + (__fh_size_t)(len_b)) \
+                ((a) < (b) && (b) < ((a) + (__fh_size_t)(len_a))) \
+             || ((b) < (a) && (a) < ((b) + (__fh_size_t)(len_b))) \
         )
 
 /*