Do not cache the results of getenv() in the temporary filename generation

logic as that might result in a UAF if an environment variable value is
modified using setenv() or similar.

FossilOrigin-Name: cefd5807d8be41f8ff0ce1ce487064dcbcf2f05583b86dbe68a3ae1960b13d9f

diff --cc manifest
index 0d613eea8b9b535965d49bb9fac1d1491198351f,3ee1ab7d269daacfc0097b6083c743b618defb90..475bd2f0f94fbb19f3e8589817291c093d1abfd9
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Remove\san\sunnecessary\smunmap()\sfrom\sthe\sunix\sinterface.
- D 2026-07-21T23:54:01.789
 -C Improvements\sto\sthe\sunix\stemporary\sfilename\sgenerator\sso\sthat\sit\scontinues\nto\swork\seven\safter\sSQLITE_TMPDIR\sor\sTMPDIR\senvironment\svariables\sare\nchanged\sby\sthe\sapplication.\s\sSimilar\schanges\sare\sneeded\sfor\sWindows.
 -D 2026-07-22T11:24:48.379
++C Do\snot\scache\sthe\sresults\sof\sgetenv()\sin\sthe\stemporary\sfilename\sgeneration\nlogic\sas\sthat\smight\sresult\sin\sa\sUAF\sif\san\senvironment\svariable\svalue\sis\nmodified\susing\ssetenv()\sor\ssimilar.
++D 2026-07-22T12:55:23.697
  F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@@ -2217,8 -2217,11 +2217,9 @@@ F tool/warnings-clang.sh bbf6a1e685e534
  F tool/warnings.sh a554d13f6e5cf3760f041b87939e3d616ec6961859c3245e8ef701d1eafc2ca2
  F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
  F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
- P 014ef252c7ea404340a5af52a6615cdddd969a4dbf30712fda538550240bb9fc
- R db35009292f15ec72dcee511d1de692d
 -P 5fc1ede8b2e559db8a5d783d1065b1f1b2eef73054486552b700706208cbdfd1
++P 5fc1ede8b2e559db8a5d783d1065b1f1b2eef73054486552b700706208cbdfd1 82e522ff1429e7eed2ffb0e960badc5757fd015023b7c0679ba32108e44e4abd
+ R 46939929c46affb76858b635fea36ba9
 -T *branch * temp-filenames
 -T *sym-temp-filenames *
 -T -sym-trunk *
++T +closed 82e522ff1429e7eed2ffb0e960badc5757fd015023b7c0679ba32108e44e4abd
  U drh
- Z 5b418561771d835342ccd84f22544807
 -Z 16e0c9db6d75dcc97770e17bbc27fe64
++Z bdf1a4651337684379b93c8dd7823792
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index 79969981913835aa29fcc917b5c9571526be84de,c905ad9c3b3abc4aaffbcb92bf26f21129e5c307..eb38ea803bed707ecb1d358ac666d715b4fb09cd
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 5fc1ede8b2e559db8a5d783d1065b1f1b2eef73054486552b700706208cbdfd1
 -82e522ff1429e7eed2ffb0e960badc5757fd015023b7c0679ba32108e44e4abd
++cefd5807d8be41f8ff0ce1ce487064dcbcf2f05583b86dbe68a3ae1960b13d9f