Initialize extra field in PgHdr1 to fix an msan complaint.

FossilOrigin-Name: 4cb2ea5795b0c0678665fd89bd560209beaab8a756fe00335dbfd07493b0542d

manifest

@@ -1,5 +1,5 @@
-C Add\sOOM\stest\scase\sassociated\swith\sthe\sfix\sin\sthe\sprevious\scommit.
-D 2021-02-27T15:32:02.041
+C Initialize\sextra\sfield\sin\sPgHdr1\sto\sfix\san\smsan\scomplaint.
+D 2021-02-28T08:24:56.477
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -534,7 +534,7 @@ F src/pager.h 4bf9b3213a4b2bebbced5eaa8b219cf25d4a82f385d093cd64b7e93e5285f66f
 F src/parse.y f3e8d7978c10495850c0bb502fe2669b55cf2841c4670b1f7261782e82069471
 F src/pcache.c 385ff064bca69789d199a98e2169445dc16e4291fa807babd61d4890c3b34177
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
-F src/pcache1.c 6596e10baf3d8f84cc1585d226cf1ab26564a5f5caf85a15757a281ff977d51a
+F src/pcache1.c 388304fd2d91c39591080b5e0f3c62cfba87db20370e7e0554062bfb29740e9f
 F src/pragma.c 6daaaecc26a4b09481d21722525b079ce756751a43a79cc1d8f122d686806193
 F src/pragma.h 8dc78ab7e9ec6ce3ded8332810a2066f1ef6267e2e03cd7356ee00276125c6cf
 F src/prepare.c f634a9e799a6b1c136d8ee12479cffa22862bfb807d307b1db406aa0cdb042a5
@@ -1908,7 +1908,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P ccb8cf5256d01b3ff13e75e1471b1afb0055ec2c344ba886f98b83d47eba00f8
-R 2795f9db27433289f60f8c83de7cdc69
+P a631c38d22bc00d38b0f112a623fb24c0e03a962f661ffe0931dad32fd31ba31
+R 121b1b49c8dd85bf7799053762dcf3af
+T *branch * msan-fix
+T *sym-msan-fix *
+T -sym-trunk *
 U dan
-Z fb78150b0343349ad1b18165979cb24b
+Z f5ed21d50100afccf53ab3ca05e5bd48

manifest.uuid

@@ -1 +1 @@
-a631c38d22bc00d38b0f112a623fb24c0e03a962f661ffe0931dad32fd31ba31
+4cb2ea5795b0c0678665fd89bd560209beaab8a756fe00335dbfd07493b0542d

src/pcache1.c

@@ -461,6 +461,7 @@ static PgHdr1 *pcache1AllocPage(PCache1 *pCache, int benignMalloc){
     p->page.pExtra = &p[1];
     p->isBulkLocal = 0;
     p->isAnchor = 0;
+    p->pLruPrev = 0;           /* Initializing this saves a valgrind error */
   }
   (*pCache->pnPurgeable)++;
   return p;