Add the SQLITE_READONLY_ROLLBACK extended error code.

Do not try to set the permissions on journal or wal files except if the
filesize is initially zero (indicating that it is a new file.)

FossilOrigin-Name: ce4ac66a4b623a3cee1a63089dd5ba8341244f1e

diff --cc manifest
index 871ea513527c59d5b4950f5f6873b6c74bc52ff8,c496616be05ffd2a468e7ae4c3ff46506c86fe3e..4aae4dfca560841c77b7729ce8ceab76590213f6
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Fix\sa\sbug\sin\sthe\srecent\sincremental-vacuum\srelated\schanges.
- D 2013-03-05T11:27:04.053
 -C Fix\san\soperator\sprecedence\sproblem\son\sthe\s[1d8086902e]\scheck-in.
 -D 2013-03-06T01:41:53.549
++C Add\sthe\sSQLITE_READONLY_ROLLBACK\sextended\serror\scode.\nDo\snot\stry\sto\sset\sthe\spermissions\son\sjournal\sor\swal\sfiles\sexcept\sif\sthe\nfilesize\sis\sinitially\szero\s(indicating\sthat\sit\sis\sa\snew\sfile.)
++D 2013-03-06T01:48:20.423
  F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
  F Makefile.in 9a804abbd3cae82d196e4d33aba13239e32522a5
  F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@@ -1036,7 -1036,7 +1036,7 @@@ F tool/vdbe-compress.tcl f12c884766bd14
  F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
  F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
  F tool/win/sqlite.vsix 97894c2790eda7b5bce3cc79cb2a8ec2fde9b3ac
- P 8e0ced1af78d8c25a06423a8e7e337ac845155cc
- R d0fc02cfce5e41e4c1a5be120b4b33d4
- U dan
- Z c4b64c03342d1e7d5813b1d9185813bd
 -P 4e6e07a60e543d5d1727cde27ab11e156202a1b8
++P 717863fca6d58828bf9321bc8b169e385ad4263f 4f5f3aebe81c3cbe539db3e33ec38fa3de47e90b
+ R 4624808bc8666139dd43b7c21e0d98ea
+ U drh
 -Z 778831793a4a16e588dea29c8ecebc95
++Z 5a1f66c8d1d16d93a8aa4820fbcfcadc

diff --cc manifest.uuid
index 95a5e3503ed3605fbcafb06006abc6c7a0c449d0,1f727ac74b3effeb5a6ba8945de7e8ea4a71b9be..1a841a4e80f060853723a59286eec60f48b4bb03
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 717863fca6d58828bf9321bc8b169e385ad4263f
 -4f5f3aebe81c3cbe539db3e33ec38fa3de47e90b
++ce4ac66a4b623a3cee1a63089dd5ba8341244f1e