Implement Mutexes and supporting syscalls, cleanup/optimize scheduler

include/m/syscall_defs.h

@@ -7,6 +7,9 @@
 #define SYS_PROC_UNMAP 4
 #define SYS_PROC_CREATE_RESOURCE_MEM 5
 #define SYS_PROC_DROP_RESOURCE 6
+#define SYS_PROC_CREATE_RESOURCE_MUTEX 7
+#define SYS_PROC_MUTEX_LOCK 8
+#define SYS_PROC_MUTEX_UNLOCK 9
 
 #define SR_OK                0
 #define SR_SYSCALL_NOT_FOUND 1
@@ -14,5 +17,6 @@
 #define SR_OOM_ERROR         3
 #define SR_NOT_FOUND         4
 #define SR_BAD_ADDRESS_SPACE 5
+#define SR_PERMISSION_ERROR  6
 
 #endif // _M_SYSCALL_DEFS_H