Merge into trunk the changes that permit :memory: databases to use shared cache.

FossilOrigin-Name: e72179f3a43e4df36b7c2955eaacce6c804272c6

diff --cc manifest
index 6b8c4fa0be621d2f8d0c717bc69f0450f98f89ce,64fa40b9fcd2b9f3a5f81eea1dc2a46ca707a234..219a7585c434418048b5c2a2b47c357ee5a2dc92
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Merge\sfts4-unicode\sbranch\swith\strunk.
- D 2012-05-26T18:42:21.996
 -C Have\suser\sinterfaces\sreport\sout\sthe\sfilename\sof\sin-memory\sdatabases\sas\san\nempty\sstring,\sas\sit\salways\shas.\s\sThis\ssimplifies\sthe\schanges.
 -D 2012-05-27T01:19:04.951
++C Merge\sinto\strunk\sthe\schanges\sthat\spermit\s:memory:\sdatabases\sto\suse\sshared\scache.
++D 2012-05-27T22:42:57.161
  F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
  F Makefile.in 2f37e468503dbe79d35c9f6dffcf3fae1ae9ec20
  F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@@ -199,8 -194,8 +199,8 @@@ F src/test9.c bea1e8cf52aa93695487baded
  F src/test_async.c 0612a752896fad42d55c3999a5122af10dcf22ad
  F src/test_autoext.c 30e7bd98ab6d70a62bb9ba572e4c7df347fe645e
  F src/test_backup.c c129c91127e9b46e335715ae2e75756e25ba27de
- F src/test_btree.c 47cd771250f09cdc6e12dda5bc71bc0b3abc96e2
+ F src/test_btree.c 5b89601dcb42a33ba8b820a6b763cc9cb48bac16
 -F src/test_config.c 0de329e736eb4aa5845069bed630e5c72f012264
 +F src/test_config.c d2da9f1490c38d9b9cb52f399b6adb81d538273a
  F src/test_demovfs.c 20a4975127993f4959890016ae9ce5535a880094
  F src/test_devsym.c e7498904e72ba7491d142d5c83b476c4e76993bc
  F src/test_func.c 090f2c3339e85c2c964435f99aed6f3da9d59525
@@@ -1004,7 -998,7 +1004,7 @@@ F tool/tostr.awk e75472c2f98dd76e06b8c9
  F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
  F tool/warnings-clang.sh a8a0a3babda96dfb1ff51adda3cbbf3dfb7266c2
  F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
- P 6d326d44fd1d626aae0e8456e5fa2049f1ce0789 e71495a817b479bc23c5403d99255e3f098eb054
- R 721b18aaca6e897933f70f12a0639abb
- U dan
- Z ae28fe2fc4311d40e0d8bc0f1e62fc1e
 -P e3ad61e0308a8442c2bdb7cdb3465576cd39ed4a
 -R c398af805389f6295630a739d754fa6b
++P 25ba1f84f2b98d50ac1e2b9849b59ee902c2cca7 595dfdbffefb2598cba89980f885289d1c5f5833
++R 5e75bcca6ded2fde27198872e2249f50
+ U drh
 -Z e51262406d85326f19add0be1c076b3b
++Z 8ecdf8c27648824577a4fdb2f7f5e787

diff --cc manifest.uuid
index fb247993c909afc496bd53dff1380b9ca0ea0842,e441849bffbf8b7988e2ae603323f994d3b34434..48122fc7387e25aa7c34e5f1802a171df41e09f0
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 25ba1f84f2b98d50ac1e2b9849b59ee902c2cca7
 -595dfdbffefb2598cba89980f885289d1c5f5833
++e72179f3a43e4df36b7c2955eaacce6c804272c6