Enhance the unix VFS so that it keeps track of the size of unlinked files

internally and thus avoids the need to call fstat() on those files, since
fstat() does not work reliably on unlinked files on some implementations
of FuseFS.

FossilOrigin-Name: 10707d35786403ea5392d980f593bfecdae063dd

diff --cc manifest
index 6555b4ed1a8dd131fa9d071618fe4b4c4fc99f50,25fcfdc03d71118ccab20b6f92b73b957130df7e..fcbd0a0c567d6e6beef95703ff58b5b631ad290e
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Modify\sthe\s%nonassoc\sdirective\sin\slemon\sso\sthat\sit\sgenerates\sa\srun-time\nerror\srather\sthan\sa\sparsing\sconflict.\s\sThis\schanges\sis\sdue\sto\sa\sbug\sreport\non\sthe\smailing\slist.\s\sSQLite\sdoes\snot\suse\sthe\s%nonassoc\sdirective\sin\sits\ngrammar\sso\sthis\schange\sdoes\snot\saffect\sSQLite.
- D 2014-06-09T13:11:40.535
 -C Enhance\sthe\sunix\sVFS\sso\sthat\sit\skeeps\strack\sof\sthe\ssize\sof\sunlinked\sfiles\ninternally\sand\sthus\savoids\sthe\sneed\sto\scall\sfstat()\son\sthose\sfiles,\ssince\nfstat()\sdoes\snot\swork\sreliably\son\sunlinked\sfiles\son\ssome\simplementations\sof\nFuseFS.
 -D 2014-06-09T20:06:01.535
++C Enhance\sthe\sunix\sVFS\sso\sthat\sit\skeeps\strack\sof\sthe\ssize\sof\sunlinked\sfiles\ninternally\sand\sthus\savoids\sthe\sneed\sto\scall\sfstat()\son\sthose\sfiles,\ssince\nfstat()\sdoes\snot\swork\sreliably\son\sunlinked\sfiles\son\ssome\simplementations\nof\sFuseFS.
++D 2014-06-09T20:24:46.164
  F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
  F Makefile.in dd2b1aba364ff9b05de41086f74407f285c57670
  F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@@ -1174,7 -1174,10 +1174,7 @@@ F tool/vdbe_profile.tcl 67746953071a9f8
  F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
  F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
  F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
- P 813469d98519b609669a004b7b604af78ef40c02
- R 17b9b9add2b8e980cb35f959c7029199
 -P 1925f3a0a2caa709569df015a8e0d26412f1a9ff
++P 1925f3a0a2caa709569df015a8e0d26412f1a9ff c41df393c6afbfbfdc4d1b885024e083c6f6de1f
+ R ce653ef517f5e803383e83307c89c5db
 -T *branch * omit-fstat-after-unlink
 -T *sym-omit-fstat-after-unlink *
 -T -sym-trunk *
  U drh
- Z c031771471155f639666c4eafbc642f6
 -Z c015ab13afaac99134c0355e5c3248ba
++Z 51e75e681608f5fd7d1d480ee0a981d3

diff --cc manifest.uuid
index 6a1ff5c5e175fadf6bd575bc25470ca7911e634e,918b2aea7b6ed9023a393ce33201591687682734..6da83fe43c8fe859c515f985a7484c7f00798e9a
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 1925f3a0a2caa709569df015a8e0d26412f1a9ff
 -c41df393c6afbfbfdc4d1b885024e083c6f6de1f
++10707d35786403ea5392d980f593bfecdae063dd