Better implementation of GetLastError. (#20623)

Instead of calling the dynamically loaded kernel32.GetLastError, we can extract it from the TEB.
As shown by [Wine](https://github.com/wine-mirror/wine/blob/34b1606019982b71818780bc84b76460f650af31/include/winternl.h#L439), the last error lives at offset 0x34 of the TEB in 32-bit Windows and at offset 0x68 in 64-bit Windows.

Author: LucasSantos91

lib/std/Thread.zig

@@ -554,7 +554,7 @@ const WindowsThreadImpl = struct {
             0,
             null,
         ) orelse {
-            const errno = windows.kernel32.GetLastError();
+            const errno = windows.GetLastError();
             return windows.unexpectedError(errno);
         };
 

lib/std/Thread/Condition.zig

@@ -178,7 +178,7 @@ const WindowsImpl = struct {
 
         // Return error.Timeout if we know the timeout elapsed correctly.
         if (rc == os.windows.FALSE) {
-            assert(os.windows.kernel32.GetLastError() == .TIMEOUT);
+            assert(os.windows.GetLastError() == .TIMEOUT);
             if (!timeout_overflowed) return error.Timeout;
         }
     }

lib/std/crypto/Certificate/Bundle.zig

@@ -132,7 +132,7 @@ fn rescanWindows(cb: *Bundle, gpa: Allocator) RescanWindowsError!void {
     cb.map.clearRetainingCapacity();
 
     const w = std.os.windows;
-    const GetLastError = w.kernel32.GetLastError;
+    const GetLastError = w.GetLastError;
     const root = [4:0]u16{ 'R', 'O', 'O', 'T' };
     const store = w.crypt32.CertOpenSystemStoreW(null, &root) orelse switch (GetLastError()) {
         .FILE_NOT_FOUND => return error.FileNotFound,

lib/std/debug.zig

@@ -1781,7 +1781,7 @@ pub const DebugInfo = struct {
 
             const handle = windows.kernel32.CreateToolhelp32Snapshot(windows.TH32CS_SNAPMODULE | windows.TH32CS_SNAPMODULE32, 0);
             if (handle == windows.INVALID_HANDLE_VALUE) {
-                switch (windows.kernel32.GetLastError()) {
+                switch (windows.GetLastError()) {
                     else => |err| return windows.unexpectedError(err),
                 }
             }

lib/std/io.zig

@@ -567,7 +567,7 @@ pub fn Poller(comptime StreamEnum: type) type {
                         windows.INFINITE,
                 );
                 if (status == windows.WAIT_FAILED)
-                    return windows.unexpectedError(windows.kernel32.GetLastError());
+                    return windows.unexpectedError(windows.GetLastError());
                 if (status == windows.WAIT_TIMEOUT)
                     return true;
 
@@ -584,7 +584,7 @@ pub fn Poller(comptime StreamEnum: type) type {
                     &self.windows.overlapped[stream_idx],
                     &read_bytes,
                     0,
-                )) switch (windows.kernel32.GetLastError()) {
+                )) switch (windows.GetLastError()) {
                     .BROKEN_PIPE => {
                         self.windows.active.removeAt(active_idx);
                         continue;
@@ -664,7 +664,7 @@ fn windowsAsyncRead(
         const buf = try fifo.writableWithSize(bump_amt);
         var read_bytes: u32 = undefined;
         const read_result = windows.kernel32.ReadFile(handle, buf.ptr, math.cast(u32, buf.len) orelse math.maxInt(u32), &read_bytes, overlapped);
-        if (read_result == 0) return switch (windows.kernel32.GetLastError()) {
+        if (read_result == 0) return switch (windows.GetLastError()) {
             .IO_PENDING => .pending,
             .BROKEN_PIPE => .closed,
             else => |err| windows.unexpectedError(err),

lib/std/os.zig

@@ -61,7 +61,7 @@ pub fn accessW(path: [*:0]const u16) windows.GetFileAttributesError!void {
     if (ret != windows.INVALID_FILE_ATTRIBUTES) {
         return;
     }
-    switch (windows.kernel32.GetLastError()) {
+    switch (windows.GetLastError()) {
         .FILE_NOT_FOUND => return error.FileNotFound,
         .PATH_NOT_FOUND => return error.FileNotFound,
         .ACCESS_DENIED => return error.PermissionDenied,