Omit mutex calls in pcache1 when the mutex is NULL, for a significant

performance improvement.

FossilOrigin-Name: caf8f574e5c64da461c6dfba8a06cf3fb18aaa42

diff --cc manifest
index f5a2a077ef7594bcf93347fe8957bec8f4104f56,2f261b5b12666736413e4548f2128ae2ed95f805..4988aa84897908a47412fc24b9bb63cc9069b762
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Minor\sperformance\soptimization\sin\spcache1.c.
- D 2015-06-12T13:04:51.385
 -C Avoid\sunnecessary\smutex\susage\sin\spcache1,\sfor\sa\ssignificant\sspeedup.
 -D 2015-06-13T11:10:55.570
++C Omit\smutex\scalls\sin\spcache1\swhen\sthe\smutex\sis\sNULL,\sfor\sa\ssignificant\nperformance\simprovement.
++D 2015-06-13T11:19:47.811
  F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
  F Makefile.in 1063c58075b7400d93326b0eb332b48a54f53025
  F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@@ -1286,7 -1286,7 +1286,8 @@@ F tool/vdbe_profile.tcl 67746953071a9f8
  F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
  F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
  F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
- P 711a176cbfad5dde6defa9648fba6d0d663af134
- R 9bc91229df1369aa902663b713f0e063
 -P 760700edb3ff1f5d6bf3058f874cc8e2808905c7
++P 2e8ad2ead9d146e312c693d9b967bbd5b92429d9 dcf4fb8d764611de60afea27cda0a8548ba7ca82
+ R caec30587447e9722ed3cdf5357476d2
++T +closed dcf4fb8d764611de60afea27cda0a8548ba7ca82
  U drh
- Z c8fd78f00b5d9acfb5119a0b1df9ec4a
 -Z 153683ea51b205873f976242b39879f7
++Z d83dc113d9069d701eaef24905e6fe62

diff --cc manifest.uuid
index 6055917edd94d118900442e051c82aafc1024518,3e458c2d08b596b72793a8352f6e83a7ee8de5ff..aa300ff2654fca95b7114f58ba3576c83342bd81
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 2e8ad2ead9d146e312c693d9b967bbd5b92429d9
 -dcf4fb8d764611de60afea27cda0a8548ba7ca82
++caf8f574e5c64da461c6dfba8a06cf3fb18aaa42