Provide the ability for the VFS to do a blocking wait on locks if compiled

with SQLITE_ENABLE_SETLK_TIMEOUT.

FossilOrigin-Name: e7dff982be753bc93123db6a0e8fefd56f2a14fd1c9a8699af0b6b75bc88fc15

diff --cc manifest
index 8bdfa78f399bda41a481d15630e61e8271a9efc7,592296d6cdfd11e86b81a1a6e364f530b3f3bf1d..a76ccd2163408763cfbd439a8f37dcc86dfd9338
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Fix\sa\stypo\spreventing\stest\sscript\savtrans.test\sfrom\srunning\sin\sauto-vacuum\nmode.
- D 2018-03-26T17:56:39.447
 -C Do\snot\sinject\sOOM\serrors\son\sSQLITE_FCNTL_LOCK_TIMEOUT\scalls\sas\san\sOOM\sis\nnot\spossible\sin\sthat\scontext.
 -D 2018-03-26T21:05:47.026
++C Provide\sthe\sability\sfor\sthe\sVFS\sto\sdo\sa\sblocking\swait\son\slocks\sif\scompiled\nwith\sSQLITE_ENABLE_SETLK_TIMEOUT.
++D 2018-03-27T13:57:31.556
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
  F Makefile.in 7016fc56c6b9bfe5daac4f34be8be38d8c0b5fab79ccbfb764d3b23bf1c6fff3
@@@ -1717,7 -1717,7 +1717,8 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P 6c40c5574f4ae9795a142d01a8f84afd1b72678ea5f6bfca14a8646c4e862605
- R c81abc7e56dd78df80782822f6e039e7
- U dan
- Z 393c2c2ceb87c77ccf0677a60f409dee
 -P b81960561b47a1b49646f2f8870dd0684dc4ca7c0b9e11076fd713de66b75972
 -R 0d3c70b064d7081aae7c053c9180f1ca
++P c7473bdb1055df06dc6a93a39ba7f56116f6866292784c4938d843531500c368 5474e560eeb0269964b70bcd876bb86b4197c4fb164bc13454fb8204f083062c
++R 6c455877087c47966ac2965f617b41ed
++T +closed 5474e560eeb0269964b70bcd876bb86b4197c4fb164bc13454fb8204f083062c
+ U drh
 -Z 20d1835935e71c19ea4ee96db7282960
++Z 6e1769ba8ee258d77420d4f502f17cc1

diff --cc manifest.uuid
index a14a88d74356d8a047b174681761998885c3417e,96991db5734a9fd4342f6868f278fd568a57649e..fdf0a47968327983ecfcedcf46d5c8c290942d16
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- c7473bdb1055df06dc6a93a39ba7f56116f6866292784c4938d843531500c368
 -5474e560eeb0269964b70bcd876bb86b4197c4fb164bc13454fb8204f083062c
++e7dff982be753bc93123db6a0e8fefd56f2a14fd1c9a8699af0b6b75bc88fc15