Merge the snapshots-always-lock-the-wal-file change into this branch.

FossilOrigin-Name: 3ec976e01550d7fb4fb76cc4896c13c86f66a141060f5fe59319434dc6119116

diff --cc manifest
index 2e5d421d031ae1dbe6042a2e9b5def0113ccfca7,0d6ebb2ca6f7c5e3a30ca0715f800f7cdc2b5ed5..6bade535bb11d5a7b0865bdd5f23f326ab131edd
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,8 -1,8 +1,8 @@@
- C Merge\slatest\strunk\schanges,\sincluding\sthe\sSQLITE_ENABLE_MULTITHREADED_CHECKS\nfeature,\sinto\sthis\sbranch.
- D 2017-11-28T08:08:40.954
 -C Lock\sthe\swal\sfile\sfor\sall\ssnapshot\stransactions,\seven\sif\sthey\swould\snot\notherwise\srequire\sthis,\spreventing\scheckpointers\sand\swriters\sfrom\swrapping\sthe\nwal\sfile.\sThis\smeans\sthat\sif\sone\sconnection\shas\san\sopen\ssnapshot\stransaction\nit\sis\sguaranteed\sthat\sa\ssecond\sconnection\scan\sopen\sa\stransaction\son\sthe\ssame\nsnapshot.
 -D 2017-11-28T13:39:41.135
 -F Makefile.in 6a879cbf01e37f9eac131414955f71774b566502d9a57ded1b8585b507503cb8
++C Merge\sthe\ssnapshots-always-lock-the-wal-file\schange\sinto\sthis\sbranch.
++D 2017-11-28T13:48:42.669
 +F Makefile.in c097996f4eea365f81c5e29a892cb198205c156a7cdfb2c3c1e10709cd419929
  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 -F Makefile.msc e5d7606238f55816da99f719969598df5b091aa2e9a6935c9412fcae8f53fc44
 +F Makefile.msc 6b76a1b3e7aa7af73ce870120ed880a288e0c7f1ee047940f62b23b514286726
  F README.md f5c87359573c4d255425e588a56554b50fdcc2afba4e017a2e02a43701456afd
  F VERSION 0c10cdfed866fdd2d80434f64f042c3330f1daaed12e54287beb104f04b3faaf
  F aclocal.m4 a5c22d164aff7ed549d53a90fa56d56955281f50
@@@ -555,8 -551,8 +555,8 @@@ F src/vdbesort.c 731a09e5cb9e96b70c394c
  F src/vdbetrace.c 48e11ebe040c6b41d146abed2602e3d00d621d7ebe4eb29b0a0f1617fd3c2f6c
  F src/vtab.c 0e4885495172e1bdf54b12cce23b395ac74ef5729031f15e1bc1e3e6b360ed1a
  F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
- F src/wal.c f940fd2e63228dede53d56a29364831f5a3f9e24232fbb9a6db3baec01f95f36
 -F src/wal.c 5a3f464edd64596f601683ed321d12e6fd93c5fb9afdfb3653d6ffd0fee9c48f
 -F src/wal.h 8de5d2d3de0956d6f6cb48c83a4012d5f227b8fe940f3a349a4b7e85ebcb492a
++F src/wal.c 605f85c9afd3bfd44008d73951e1f1fa64263bcddd7cc5e03b339a9dd7ccd1d5
 +F src/wal.h bada9007800e82f2765ad9ecd9f96176b45c71db769502e24de49d68c0acef65
  F src/walker.c da987a20d40145c0a03c07d8fefcb2ed363becc7680d0500d9c79915591f5b1f
  F src/where.c 9752b68e03e2044f0faa4708fabb0189769067b660bffa931e1fd65736269659
  F src/whereInt.h 82c04c5075308abbac59180c8bad5ecb45b07453981f60a53f3c7dee21e1e971
@@@ -1683,7 -1679,8 +1684,7 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
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  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P e2b3e33537384633a1c160f1fc9c78d515684c942c2446eb339f375d10a42000 40b598c8392f030f6ed8c63ce81cb0426bb3984397c19c756215f6a569a40164
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++P 1fd1034935b932e9e0a29b26931f7ccf9fb0bda916c4fa8b741bf6f48f124dda b81a31495bd27c1d96f7df653da3502054240cb5acf66b860da7f0f9b422a524
++R ce1e563938f18a80da5f4163a06f5f4a
  U dan
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++Z 83a12225ed775f5cde42826fd19f9630

diff --cc manifest.uuid
index 98e256df42482b70a66f82b007daef85ba906f58,1c080520c0a753d9ee3b6581230e526640d3de2a..dc8d42c11f009e62225113511951f5be68cc11c1
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 1fd1034935b932e9e0a29b26931f7ccf9fb0bda916c4fa8b741bf6f48f124dda
 -b81a31495bd27c1d96f7df653da3502054240cb5acf66b860da7f0f9b422a524
++3ec976e01550d7fb4fb76cc4896c13c86f66a141060f5fe59319434dc6119116

diff --cc src/wal.c
Simple merge