Reduce the default SQLITE_MAX_MMAP_SIZE slightly so that it fits in a
signed 32-bit integer.

FossilOrigin-Name: 460752b8575320163d2659bb7ff24aff41e2bb66
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 876629a..b041b3f 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -563,7 +563,7 @@
   || defined(_WIN32) \
   || (defined(__APPLE__) && defined(__MACH__)) \
   || defined(__sun)
-#   define SQLITE_MAX_MMAP_SIZE 2147483648
+#   define SQLITE_MAX_MMAP_SIZE 0x7fff0000  /* 2147418112 */
 # else
 #   define SQLITE_MAX_MMAP_SIZE 0
 # endif