Revert of Replace basictypes.h with stdint.h for int_t types. (patchset #1 id:1 of https://codereview.webrtc.org/2604043002/ )

Reason for revert:
Very likely cause of Chromium import bot breakage (unused function '__cpuid'), TBD why.

Original issue's description:
> Replace basictypes.h with stdint.h for int_t types.
>
> Removes basictypes.h for types that only makes use of it for fixed-size-int
> typedefs and replaces it with stdint.h.
>
> BUG=webrtc:6853
> R=tommi@webrtc.org
>
> Review-Url: https://codereview.webrtc.org/2604043002
> Cr-Commit-Position: refs/heads/master@{#15867}
> Committed: https://chromium.googlesource.com/external/webrtc/+/7fd1a753005ca93e8bd934a55808a2137b0ad84f

TBR=tommi@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:6853

Review-Url: https://codereview.webrtc.org/2603203003
Cr-Commit-Position: refs/heads/master@{#15869}
diff --git a/webrtc/base/byteorder_unittest.cc b/webrtc/base/byteorder_unittest.cc
index 6d9b44f..c3135aa 100644
--- a/webrtc/base/byteorder_unittest.cc
+++ b/webrtc/base/byteorder_unittest.cc
@@ -8,9 +8,9 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include <stdint.h>
-
 #include "webrtc/base/byteorder.h"
+
+#include "webrtc/base/basictypes.h"
 #include "webrtc/base/gunit.h"
 
 namespace rtc {