Add a mutex to the sqlite3_db_config() interface so that it is threadsafe

when two or more threads call it on the same database connection at the same
time.

FossilOrigin-Name: 459ad8846ee1ee2d3b277a291c47121692bdf477e779b06e77be8338f62237a6

manifest

@@ -1,5 +1,5 @@
-C Fix\san\sinefficiency\sin\sthe\s".dump"\scommand\swhen\soutputing\slarge\sblob\sliterals.
-D 2022-08-24T11:51:31.345
+C Add\sa\smutex\sto\sthe\ssqlite3_db_config()\sinterface\sso\sthat\sit\sis\sthreadsafe\nwhen\stwo\sor\smore\sthreads\scall\sit\son\sthe\ssame\sdatabase\sconnection\sat\sthe\ssame\ntime.
+D 2022-08-24T17:59:00.857
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -552,7 +552,7 @@ F src/insert.c aea5361767817f917b0f0f647a1f0b1621bd858938ae6ae545c3b6b9814b798f
 F src/json.c 7749b98c62f691697c7ee536b570c744c0583cab4a89200fdd0fc2aa8cc8cbd6
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 853385cc7a604157e137585097949252d5d0c731768e16b044608e5c95c3614b
-F src/main.c 211f5fd4110b0565fc2135d60ed12b4ef8a29d634414f471b5f957aa7b7f2afa
+F src/main.c 8983b4a316d7e09946dd731913aa41712f02e2b55cb5c6c92126ccfe2473244a
 F src/malloc.c b7a3430cbe91d3e8e04fc10c2041b3a19794e63556ad2441a13d8dadd9b2bafc
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
@@ -1999,8 +1999,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 34b8ea31877ae8b40729d37b3f51ae7e15f38be841881ea4a37c9c8f0a52896d
-R dc24309269ebb0196ddc57abadbebde7
-U dan
-Z dc08be03d0061be2657759d58bd54896
+P c055d05dbdfd4643d5052c6e6a736c78651fdfcd78f15f791af903df3814832d
+R ffd7ba0b6070375035a4339c90c0b447
+U drh
+Z c6fbe2adc7008df263b408289cea2842
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-c055d05dbdfd4643d5052c6e6a736c78651fdfcd78f15f791af903df3814832d
+459ad8846ee1ee2d3b277a291c47121692bdf477e779b06e77be8338f62237a6

src/main.c

@@ -915,6 +915,7 @@ int sqlite3_db_cacheflush(sqlite3 *db){
 int sqlite3_db_config(sqlite3 *db, int op, ...){
   va_list ap;
   int rc;
+  sqlite3_mutex_enter(db->mutex);
   va_start(ap, op);
   switch( op ){
     case SQLITE_DBCONFIG_MAINDBNAME: {
@@ -980,6 +981,7 @@ int sqlite3_db_config(sqlite3 *db, int op, ...){
     }
   }
   va_end(ap);
+  sqlite3_mutex_leave(db->mutex);
   return rc;
 }