Add support for the SQLITE_DBCONFIG_MAINDBNAME configuration option.

FossilOrigin-Name: 7839519349c7371cdb4e16a215eacd27004cbc62

diff --cc manifest
index 2c686caa9b5d42b8978a638a80ddb5b7d5cce7dc,0c9709e64d0cebb234a8bddcb28090c62423c6a2..f6da52a9f535b5aa05bb9687823431dc819d0d87
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Enhance\sthe\sVACUUM\scommand\sso\sthat\sit\scan\soperate\son\san\sattached\sdatabase.
- D 2016-08-19T15:15:55.612
 -C Merge\sthe\sVACUUM\sattached\sdatabase\senhancement\sfrom\strunk.
 -D 2016-08-19T15:17:51.033
++C Add\ssupport\sfor\sthe\sSQLITE_DBCONFIG_MAINDBNAME\sconfiguration\soption.
++D 2016-08-22T20:10:01.543
  F Makefile.in cfd8fb987cd7a6af046daa87daa146d5aad0e088
  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
  F Makefile.msc d66d0395c38571aab3804f8db0fa20707ae4609a
@@@ -1511,8 -1511,7 +1511,8 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P cb9865e14db1c0076618f13400151112f84960cb ad35ef116296e5d6aaeb9ef260bf35bee3bd6d20
- R abd29f9f3d87c2af53d085425233b2a6
- T +closed ad35ef116296e5d6aaeb9ef260bf35bee3bd6d20
 -P d6e3d5796c9991ca0af45ed92ce36f55efc02348 083f9e6270fa4faa402b91231271da4f3915c79f
++P 083f9e6270fa4faa402b91231271da4f3915c79f 12d5e38d269ede27cd38a031a395915301fffe56
+ R a6e4b4d3ce0ef3f2cf848bb14d9b8323
++T +closed 12d5e38d269ede27cd38a031a395915301fffe56
  U drh
- Z a6de375e7bb722769082d6e640b9c49b
 -Z 52253f5e7188c5e562d511d2d515cb7a
++Z 7e1aff0002b8c240c3859f075858093c

diff --cc manifest.uuid
index 4e9d48c81e556bd04a4d5b82df5a69b78f2bbe75,b09f072000e754b1678e89768b7aace36809f3b0..b5392b6178b7e612818b715314513d512385f4d9
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 083f9e6270fa4faa402b91231271da4f3915c79f
 -12d5e38d269ede27cd38a031a395915301fffe56
++7839519349c7371cdb4e16a215eacd27004cbc62