Fix leap-year handling for dates prior to 0400-03-01.

[forum:/forumpost/eaa0a09786c6368b|Forum post eaa0a09786c6368b].

FossilOrigin-Name: 474b7e34b83bc5e85854bc3b386f31ff39b390549d89b94921f33bbc5b658d1d

diff --cc manifest
index 15c9bb12035e123f0f92c6d4436baea1c3e3c5a7,912b177c8462342377103640f0ca7f2c6e832e86..36c6ec2d08ac813817737c281bc34fa20ae8319d
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Automatically\sdisable\sdirectory\sfsync\swhen\scompiling\sfor\sAIX.
- D 2024-08-18T09:53:37.962
 -C New\sdate/time\stest\scases\sto\svalidate\sancient\sdates.
 -D 2024-08-19T13:53:49.904
++C Fix\sleap-year\shandling\sfor\sdates\sprior\sto\s0400-03-01.\n[forum:/forumpost/eaa0a09786c6368b|Forum\spost\seaa0a09786c6368b].
++D 2024-08-19T14:20:18.155
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
  F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@@ -2205,8 -2206,8 +2206,9 @@@ F vsixtest/vsixtest.tcl 6195aba1f12a5e1
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P a4043cbeb8a08fca2fdd2ea703e030d3a5574cc6002292ecc6f0e88c116472a3
- R cd57173ec450b44036cf8242b7c2fe1f
 -P 00cae11fffaf50e2133915e851d41098d00b6b1458e1438bcb6664e1411d8498
++P 8d170e07e20c21a5bb97fdc8c2d01d92178f5fe740e60d203e4621747cfce33e 82719074f090d9d0a0b9baea0dee7b1dd40a272e3f3e45043d4a640c07989d5d
+ R 020e143aeb047149147ee2aa5a7ba85f
++T +closed 82719074f090d9d0a0b9baea0dee7b1dd40a272e3f3e45043d4a640c07989d5d
  U drh
- Z a06494827a8461d8ba3867ea1f761ae1
 -Z d05bb26a1492de783006f86a1565084e
++Z 9fbf7737d861801920bb81b27dfd5b14
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index 1dca61d1bd10f03d3702145db7a9117d2ab1114a,40201f610b3c355d39b4d43d07389dee3662e8ee..aa398a661d38d22034e2e477d6e3904a77ef6301
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 8d170e07e20c21a5bb97fdc8c2d01d92178f5fe740e60d203e4621747cfce33e
 -82719074f090d9d0a0b9baea0dee7b1dd40a272e3f3e45043d4a640c07989d5d
++474b7e34b83bc5e85854bc3b386f31ff39b390549d89b94921f33bbc5b658d1d