organize std lib concurrency primitives and add RwLock

 * move concurrency primitives that always operate on kernel threads to
   the std.Thread namespace
 * remove std.SpinLock. Nobody should use this in a non-freestanding
   environment; the other primitives are always preferable. In
   freestanding, it will be necessary to put custom spin logic in there,
   so there are no use cases for a std lib version.
 * move some std lib files to the top level fields convention
 * add std.Thread.spinLoopHint
 * add std.Thread.Condition
 * add std.Thread.Semaphore
 * new implementation of std.Thread.Mutex for Windows and non-pthreads Linux
 * add std.Thread.RwLock

Implementations provided by @kprotty

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/std/event/wait_group.zig b/lib/std/event/wait_group.zig
index d123f7df27..0b83c18c74 100644
--- a/lib/std/event/wait_group.zig
+++ b/lib/std/event/wait_group.zig
@@ -30,7 +30,7 @@ pub fn WaitGroupGeneric(comptime counter_size: u16) type {
     return struct {
         counter: CounterType = 0,
         max_counter: CounterType = std.math.maxInt(CounterType),
-        mutex: std.Mutex = .{},
+        mutex: std.Thread.Mutex = .{},
         waiters: ?*Waiter = null,
         const Waiter = struct {
             next: ?*Waiter,