Fix Dovecot quota overflow on old Slackware (libc 2.3.1)

--- src/plugins/quota/quota-fs.c.orig   2017-06-08 15:30:17.000000000 -0700
+++ src/plugins/quota/quota-fs.c        2017-06-08 15:30:17.000000000 -0700
@@ -584,10 +584,10 @@
                }

                /* values always returned in 512 byte blocks */
-               *bytes_value_r = xdqblk.d_bcount * 512;
-               *bytes_limit_r = xdqblk.d_blk_softlimit * 512;
+               *bytes_value_r = xdqblk.d_bcount * 512ULL;
+               *bytes_limit_r = xdqblk.d_blk_softlimit * 512ULL;
                if (*bytes_limit_r == 0) {
-                       *bytes_limit_r = xdqblk.d_blk_hardlimit * 512;
+                       *bytes_limit_r = xdqblk.d_blk_hardlimit * 512ULL;
                }
                *count_value_r = xdqblk.d_icount;
                *count_limit_r = xdqblk.d_ino_softlimit;
@@ -618,13 +618,13 @@
                }

 #if _LINUX_QUOTA_VERSION == 1
-               *bytes_value_r = dqblk.dqb_curblocks * 1024;
+               *bytes_value_r = dqblk.dqb_curblocks * 1024ULL;
 #else
                *bytes_value_r = dqblk.dqb_curblocks;
 #endif
-               *bytes_limit_r = dqblk.dqb_bsoftlimit * 1024;
+               *bytes_limit_r = dqblk.dqb_bsoftlimit * 1024ULL;
                if (*bytes_limit_r == 0) {
-                       *bytes_limit_r = dqblk.dqb_bhardlimit * 1024;
+                       *bytes_limit_r = dqblk.dqb_bhardlimit * 1024ULL;
                }
                *count_value_r = dqblk.dqb_curinodes;
                *count_limit_r = dqblk.dqb_isoftlimit;