Add experimental feature to detect threading bugs in apps that use

SQLITE_CONFIG_MULTITHREADED. Enabled at compile time using
SQLITE_ENABLE_MULTITHREADED_CHECKS.

FossilOrigin-Name: 40b598c8392f030f6ed8c63ce81cb0426bb3984397c19c756215f6a569a40164

diff --cc manifest
index 9d698eeef137e0f41e130b748dbabbbcc62f3f3b,6f5326f179801fa9627c8c463efa8398aee91780..58ec6b902608fade07222a805cd28cf18ff3a4e3
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Update\stests\sto\sdeal\swith\sSQLITE_FAST_SECURE_DELETE.
- D 2017-11-28T00:52:14.148
 -C Use\sa\ssymbolic\sconstant\sinstead\sof\sa\sliteral\s(-1)\sto\sidentify\sa\nwarn-on-contention\smutex.
 -D 2017-11-28T07:47:57.520
++C Add\sexperimental\sfeature\sto\sdetect\sthreading\sbugs\sin\sapps\sthat\suse\nSQLITE_CONFIG_MULTITHREADED.\sEnabled\sat\scompile\stime\susing\nSQLITE_ENABLE_MULTITHREADED_CHECKS.
++D 2017-11-28T07:52:00.416
  F Makefile.in 6a879cbf01e37f9eac131414955f71774b566502d9a57ded1b8585b507503cb8
  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
  F Makefile.msc e5d7606238f55816da99f719969598df5b091aa2e9a6935c9412fcae8f53fc44
@@@ -1678,7 -1678,7 +1678,8 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P 465350e55ddaf30cfba7874653301de7238a9dc2bc5e1f800fc95de9360679f6
- R 5c3698b136ad7029a7e22749e9f1a061
- U drh
- Z 455c99a49ae132932748abfe00c111c4
 -P 7d0b12fcb58353b883ffce77df824a5cc8b1e913a21ec3f22fb73481a398c916
 -R a940a7b7e2663c64f019728def2f503f
++P e6b89304695be371978e65dddd710c8bd563c66b9c94d23165142b6c235c82e1 12a23c0a66fac5c9674120b390f6abaeaba3f7ff04693b281af1eefb93d6f47c
++R dd8aff31239aebcaa5e5379a4673912d
++T +closed 12a23c0a66fac5c9674120b390f6abaeaba3f7ff04693b281af1eefb93d6f47c
+ U dan
 -Z d7c77380d4461a6101913d9af19a0151
++Z bdded6a608898929c58df7d45769809f

diff --cc manifest.uuid
index 289fbf551521e598b7f4b699af3416e366f62124,60dae679391904bcf81be7b03ed6a5525d4f248c..2cef934b2b6c22cc41e0387c0fcd153249dabc1e
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- e6b89304695be371978e65dddd710c8bd563c66b9c94d23165142b6c235c82e1
 -12a23c0a66fac5c9674120b390f6abaeaba3f7ff04693b281af1eefb93d6f47c
++40b598c8392f030f6ed8c63ce81cb0426bb3984397c19c756215f6a569a40164