Merge pull request #2680 from BernardXiong/pthreads

[pthreads] Change the pthreads management.

Author: BernardXiong

components/libc/Kconfig

@@ -8,6 +8,12 @@ config RT_USING_PTHREADS
     bool "Enable pthreads APIs"
     default n
 
+if RT_USING_PTHREADS
+    config PTHREAD_NUM_MAX
+    int "Maximum number of pthreads"
+    default 8
+endif
+
 if RT_USING_LIBC && RT_USING_DFS
     config RT_USING_POSIX
         bool "Enable POSIX layer for poll/select, stdin etc"