When shutting down the memsys5 memory allocator, be sure to clear the mutex

pointer in case the next startup does not use a mutex because it is configured
differently.

FossilOrigin-Name: d4e7e2d82321c12fe471ed49098828bc0ef78543

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
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-D 2009-08-18T01:54:19
+C When\sshutting\sdown\sthe\smemsys5\smemory\sallocator,\sbe\ssure\sto\sclear\sthe\smutex\npointer\sin\scase\sthe\snext\sstartup\sdoes\snot\suse\sa\smutex\sbecause\sit\sis\sconfigured\ndifferently.
+D 2009-08-18T12:16:03
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 0f7761c5d1c62ae7a841e3393ffaff1fa0f5c00a
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -135,7 +135,7 @@ F src/mem0.c f2f84062d1f35814d6535c9f9e33de3bfb3b132c
 F src/mem1.c e6d5c23941288df8191b8a98c28e3f57771e2270
 F src/mem2.c d02bd6a5b34f2d59012a852615621939d9c09548
 F src/mem3.c 67153ec933e08b70714055e872efb58a6b287939
-F src/mem5.c 51f22f4783c974e4470ed25df4eefb4cfe00be86
+F src/mem5.c 985413fcb066de2f1ec958f4a4ec753a7fdcdafa
 F src/memjournal.c e68cb5f7e828b84d5bf2ea16c5d87f1ed7e9fe7f
 F src/mutex.c 73899d158560117c02909b6e9ffe2bad2560a817
 F src/mutex.h 9e686e83a88838dac8b9c51271c651e833060f1e
@@ -749,14 +749,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl 672f81d693a03f80f5ae60bfefacd8a349e76746
-P b98a8706a61ad27c881b6820eee10d06bfb27417
-R 55b70508511043089513b3f1c6289087
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+R a6b0c6db08939ff844e895f138661e73
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+Z 9c3385b37c1b092f6192eca52ea5212d
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manifest.uuid

@@ -1 +1 @@
-783b751a38f9f911c5ebdf738c255b7111978f76
+d4e7e2d82321c12fe471ed49098828bc0ef78543

src/mem5.c

@@ -472,6 +472,7 @@ static int memsys5Init(void *NotUsed){
 */
 static void memsys5Shutdown(void *NotUsed){
   UNUSED_PARAMETER(NotUsed);
+  mem5.mutex = 0;
   return;
 }