Update pl-inline.h: less intrusive change

That change silences the warning too.

So either the array-bounds warning is a false positive, or the assertion n%sizeof(word) isn't always met.

src/pl-inline.h

@@ -762,7 +762,9 @@ murmur_key(const void *ptr, size_t n)
 
     for(size_t i=0; i<KEY_INDEX_MAX-2; i++)
       data[i] = in[i];
-    data[KEY_INDEX_MAX-2] = in[n/sizeof(word)-2];
+
+    /* the extra n%... silences a -Warray-bounds warning */
+    data[KEY_INDEX_MAX-2] = in[n/sizeof(word) - n%sizeof(word) - 1];
     data[KEY_INDEX_MAX-1] = n;
 
     k = MurmurHashAligned2(data, sizeof(word)*4, MURMUR_SEED);