Fix typo (thread_cache should be thread_cache_size) in example

configuration files. (Bug #13811)

support-files/my-huge.cnf.sh

@@ -33,7 +33,7 @@ sort_buffer_size = 2M
 read_buffer_size = 2M
 read_rnd_buffer_size = 8M
 myisam_sort_buffer_size = 64M
-thread_cache = 8
+thread_cache_size = 8
 query_cache_size = 32M
 # Try number of CPU's*2 for thread_concurrency
 thread_concurrency = 8

support-files/my-innodb-heavy-4G.cnf.sh

@@ -128,7 +128,7 @@ join_buffer_size = 8M
 # the amount of thread creations needed if you have a lot of new
 # connections. (Normally this doesn't give a notable performance
 # improvement if you have a good thread implementation.)
-thread_cache = 8
+thread_cache_size = 8
 
 # This permits the application to give the threads system a hint for the
 # desired number of threads that should be run at the same time.  This

support-files/my-large.cnf.sh

@@ -33,7 +33,7 @@ sort_buffer_size = 1M
 read_buffer_size = 1M
 read_rnd_buffer_size = 4M
 myisam_sort_buffer_size = 64M
-thread_cache = 8
+thread_cache_size = 8
 query_cache_size= 16M
 # Try number of CPU's*2 for thread_concurrency
 thread_concurrency = 8