Avoid computing the values for unused result-set columns in subqueries.

Performance optimization request [baa5bb76c35a124c].

FossilOrigin-Name: 7c2d3406000dc8ac5a99cc205b036356b67e4b0b94738592ffc5680749696904

diff --cc manifest
index cec9479716c278c7397d431872efc11419539fc9,8350761a552fe9f31c27d8a660a34cb86a3f3499..65bf1958f6cead0721a950afac728e515ed2ee9b
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Update\sthe\sversion\snumber\sto\s3.42.0\sto\sbegin\sthe\snext\sdevelopment\scycle.
- D 2023-02-22T20:50:51.768
 -C A\sfew\ssimple\stest\scases\sfor\sthe\somit-unused-subquery-column\soptimization.
 -D 2023-02-16T19:41:39.707
++C Avoid\scomputing\sthe\svalues\sfor\sunused\sresult-set\scolumns\sin\ssubqueries.\nPerformance\soptimization\srequest\s[baa5bb76c35a124c].
++D 2023-02-22T21:11:34.555
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
  F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@@ -621,12 -621,12 +621,12 @@@ F src/printf.c ff4b05e38bf928ff1b80d3dd
  F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
  F src/resolve.c d62c5665279cc7485f9d45b5e20911cc7b19c203f268321a90d05d74f4725750
  F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
- F src/select.c f80d98f13fa64201ababf5e80d682c430559cd7ee00ab14ee99a1aeb27ac097d
 -F src/select.c fa66a61608731b4842fb2a2799ddeccbb56b4ec863f8b36d8b08b898ff62067a
 -F src/shell.c.in 5cb750dc00bb8b20b020031fd1bb0cb8759a6e567c27aee6b0af31d187984985
 -F src/sqlite.h.in c060f9e6f646fd817abf273c068666e079fc6e8467ea1d3e8b20f355f82722e9
++F src/select.c 751d2f021cb439abdf3e8e7b74c5d0532ca9793868e4fb4c5a73412aea274edc
 +F src/shell.c.in 6f36f5ca05f1bebf74935a7fcf2dce983016e807a09cbd752a673583ad7da087
 +F src/sqlite.h.in 662a2fa083d093896b92560c871dea6d86792b49dc4bf7b4e8dbeca8e7171488
  F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
  F src/sqlite3ext.h da473ce2b3d0ae407a6300c4a164589b9a6bfdbec9462688a8593ff16f3bb6e4
- F src/sqliteInt.h 4dcc36b21dd0c77efeb0bb38b0d31916bc63fb429c8a89d186c945eba0816447
+ F src/sqliteInt.h 25f38ade2d93828231d6cd8614f635c0b084bee004360d970542861ad2e3e3d8
  F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
  F src/status.c 160c445d7d28c984a0eae38c144f6419311ed3eace59b44ac6dafc20db4af749
  F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@@ -2045,8 -2046,8 +2046,9 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P aa6bd6dff751223e302575c60f335707e4bb820bff716cab3706b564e18ed7ed
- R 311ae6e51c5af4c947ddc5fe5e93f886
 -P 6b1a1f374d1372f11f5420d99645b218867100bf070bd3a8885bf5f00c189dff
 -R 1e3c678f9fbc9f1a9649605265913343
++P 65910216393ed287dbc7e42a2598b6980183c62a64da6572cb691ff4ee23555d cf8f57c53425d89619ece10edc197d7d28946d3b23fcb4f526330196c76d9cc1
++R 34649150ad57f18afb1178077e5cdae5
++T +closed cf8f57c53425d89619ece10edc197d7d28946d3b23fcb4f526330196c76d9cc1
  U drh
- Z 558b030af06c9bbcf0267311941c1842
 -Z 7d95cef9a9f7a288c86a6fe2f6e032bb
++Z c744fac449b59dcb5adcaf0108c5c30e
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index fe2ab7c19f86d7a8837782752f59689fde12ccbb,3216d50cee67056057d4bf199c89144c99503af6..4b12d53327ccd4f7638a44c4a7d142314e76e98c
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 65910216393ed287dbc7e42a2598b6980183c62a64da6572cb691ff4ee23555d
 -cf8f57c53425d89619ece10edc197d7d28946d3b23fcb4f526330196c76d9cc1
++7c2d3406000dc8ac5a99cc205b036356b67e4b0b94738592ffc5680749696904

diff --cc src/select.c
Simple merge