Correct a typo error: cpp symbol is "BIG_TABLES", not "BIG_FILES".

configure.in:
  Defining "BIG_TABLES" works around a problem with the Sun Forte 
  compiler for Solaris on x86 platforms: improper handling of "long long".
  Error shows up on the "limit_rows_found" variable in test "union".
  Old "BIG_FILES" was a typing error.

configure.in

@@ -972,8 +972,8 @@ MAX_CXX_OPTIMIZE="-O3"
 # workaround for Sun Forte/x86 see BUG#4681
 case $SYSTEM_TYPE-$MACHINE_TYPE-$ac_cv_prog_gcc in
   *solaris*-i?86-no)
-    CFLAGS="$CFLAGS -DBIG_FILES"
-    CXXFLAGS="$CXXFLAGS -DBIG_FILES"
+    CFLAGS="$CFLAGS -DBIG_TABLES"
+    CXXFLAGS="$CXXFLAGS -DBIG_TABLES"
     ;;
   *) ;;
 esac